UKC

Hi, I use a KVM switch so that I can have one monitor, keyboard and mouse shared between two computers (a Dell laptop for work, which I use in dual monitor mode, and my personal Mac Mini)
Keyboard is wired, mouse is wireless to a USB dongle. 
The KVM is reliable only around 70% of the time. Unacceptably frequently, I have issues such as: the monitor reports no signal from HDMI;
there is no response when switching from one computer to the other;
there is response when switching, but the keyboard and/or mouse become totally unresponsive through the KVM

Generally this is fixed by disconnecting and reconnecting all seven inputs to the KVM, but I shouldn't have to deal with this. In some cases, this doesn't even solve it and there are random fixes involving shutting down both computers and connecting everything just to one computer directly, and then gently introducing the KVM into the chain. 

It is an Ablewe that I bought from Amazon 2 years ago: KVM Switch HDMI 2 Port Box,ABLEWE USB and HDMI Switch for 2 Computers Share Keyboard Mouse and one HD Monitor,Support UHD 4K@30Hz,with 2 USB Cable and 2 HDMI Cable, and is around £27.

The frequency of these dropouts is increasing. 

Have I got a duff one, or do they all "just do this", or is £27 the cheap and nasty end of KVM switches?

I've just now had my worst battle with the bloody thing and it has put me in a rather grumpy mood not befitting a Friday evening....

Any advice is appreciated.

(Just for fun I have a third PC for this set up but I don't want to complicate things too much - it's rarely used and its display output uses DisplayPort and I just connect it directly and live with my laptop just as a laptop and ignore my Mac Mini, when this third PC is needed!)

I’ve deployed a lot of and they have been pretty reliable:

https://business.currys.co.uk/catalogue/computing/components-upgrades/cable...

I’ve no idea if Curry’s is the cheapest option, though.

This probably won't be your favourite reply, but I have one PC with 3 screens and wireless mouse and 1986 AT keyboard, and I use remote desktop to access two other PCs and various things on the internet.

In the past I used to use a MacBook with a Thunderbolt screen and magic mouse to connect to PCs, but sadly the mouse gave me RSI so I had to abandon it; and there was only one screen even though it was a cracker.

I haven't used a KVM for well over twenty years.

I've a similar device and very occasionally my windows laptop doesn't recognise the monitor has switched. My MacBook is always fine but my older MacBook was also intermittent. 

So could also be a driver issue? As its a locked down windows laptop I can't tinker with drivers so just switch back to the Mac and immediately back to the windows one and it fires straight up.

Thanks, I have no issue with the reply but it does seem to describe a rather different scenario. I admit to having some "fear and distrust" (based on ignorance and incompetence mostly but also partly on observation of supposed/self-declared skilled IT guru colleagues arrogantly assuming they can set up Remote Desktop, failing, and blaming things other than themselves and their assumptions )

I'd be willing to give that a try. When you say "pretty reliable", is that better than my 70%?

A quick Google search implies that Currys perhaps surprisingly is the cheapest although there is not much in it. I can perhaps(*) bill it to my employers anyway


* = 100% I would do this

For a 2 computer set-up, just using the monitor options with different inputs and mapping the USB ports on the monitor to the different video in settings. Your monitor may be able to do this. Mine has three video inputs and I have a Mac and PC attached via DVI and HDMI and as you swap input the monitor changes the USB input. However I find having this combination a little awkward as a PC keyboard on the Mac is not the best so I now have a bluetooth keyboard for the Mac.

Thanks Steve, I’ll try this later this evening. If it works it sounds it could even be a neat solution for the third PC. I have got used to using a PC keyboard for the Mac, somehow! But I know what you mean.

I just have all my peripherals through a cheap usbc hub, and just plug it into whichever computer I'm using.

It's 100% reliable.

They work reliably, and of the 100 or so deployed, only a couple have packed up in the five years since installation.

thanks for the stats! 😃

hah, as I’d thought, my monitor has no USB ports. That’s that then! It is sold as a gaming monitor and bought in the recommendation of a trusted (and also non-gaming) friend 

Mind you, many cheaper KVMs like that Aten only support 1080p ("Full HD") resolution, which IMHO in this day and age is pretty ugly even for just reading the web. HDMI and DP come in many versions, and the earlier versions can only manage HD or at best 4K @ 30Hz. Confused about too many differing standards and their versions? Well, we just need to add another standard to the lot, that will definitely solve it

Thanks for this Frank, quite interesting! The information you don't have, is that my external monitor is only a 28". Its an ASUS TUF Gaming VG289Q 28-inch, 4K UHD, IPS display. In 3 years of using this Mac Mini I had not even paid attention to the display resolution - it defaulted to 1920 x 1080 on direct connection and I was happy with this. I wonder if you comment relates to larger monitors, or if my eyes are just not conditioned to higher resolution? When I set it to max resolution 3840 x 2160, as you know, "everything goes tiny". Might be nice for watching high res video output but I don't do much of that! Incidentally my existing KVM (currently behaving!) happily communicates this resolution even though my cables aren't anything special. 
As for my Dell work laptop, it maxes out at 1920 * 1080 anyway. 
I did also check putting the HDMI from each machine, directly into HDMI 1 and 2 on the monitor and using the KVM only for switching keyboard and mouse controls (with the additional consideration of biting the bullet and actually having separate keyboard and mouse for each machine, and just switching the HDMI on the monitor itself) but there was no difference. 

So for now, I'll stick with this KVM unit and see if I can tolerate soldiering on with it, with the option to get the ATEN suggested upthread. 

 

I use a Greathtek USB 2.0 KVM Switch 2 Port.

Set it up about 4 years ago for swapping between my main workstation (2 monitors) and various laptops provided for contract work. For each laptop I simply plug in the monitor cable and a USB cable and I can swap easily between a laptop and my workstation by pressing the button on the KVM switch.

I have never had a problem with it. All the devices work fine, even the wireless mouse. Below is a photo of the KVM switch.

Thanks, that's now two recommendations for an an alternative I'll see how many times I have to faff with mine over the next two weeks, and if it's unacceptable to me, I'll try one of these alternatives. 

The Display settings on any vaguely modern version of macOS does not indicate the actual display resolution of your monitor in pixels but in 'points'. The default resolution of 1920x1080 is more than likely using your monitor's resolution in pixels of 3840x2160 and 'points' are scaled to your display with a scaling factor of x2.

When you change the resolution on the settings to 3840x2160 the monitor will still be using the monitor resolution of 3840x2160 as before but macOS will scale to your screen with a scaling factor of points to pixels of x1. Which, as you say, means "everything goes tiny".

The settings app does not show the scaling factor, it's hidden from users although you can obtain it programmatically from a display if you need to.

So basically stick with the default resolution, it will be using the maximum resolution of your monitor already.

Thanks, that all makes sense as the image looks fine (as opposed to shonky set-ups that enlarge a lower resolution to fill a screen, and become pixellated)

Hilariously the bloody KVM has this afternoon decided to stop transmitting any signal from my Mac Mini, even with two "pull all the cables out and swap them over" actions.....

What's your Mac Mini? You'd definitely need at least HDMI 2.0 capable KVM (or its equivalent in DisplayPort) for it to work properly, I think. As MeMeMe explained, your Mac still uses the full 4K, but by smartly rendering all the text and using bigger icons, it makes everything sharper, not smaller. HDMI 2.0 is the earliest version that supports 4K at full 60Hz, which is the minimum you need, so look for either HDMI 2.x, 4K@60Hz or similar. A fair warning – those are all more expensive.

Cheers. Just pulled up the spec from my original order (I am not at the computer now so can't pull up its info)

Apple M1 chip with 8‑core CPU, 8‑core GPU, and 16‑core Neural Engine

16GB unified memory

512GB SSD storage

GRAPHICS 065-C9F5 8-CORE GPU


Where you mention HDMI 2.0 and 60Hz are you talking about cables or KVMs? I just have cheap generic HDMI cables, my KVM apparently supports 4K at 60Hz but my display settings show 30Hz whether through KVM or directly. Whether this is governed by computer, cable, KVM or monitor, I don't know. But I am happy with the display as it is! 


This is what I have, enjoy the "Engrish"

https://www.ablewe.com/kvm-switch-hdmi-2-port-boxablewe-usb-and-hdmi-switch...

Ah, if your display settings show 30Hz, something is definitely wrong with your setup – either the KVM, or (from your note more likely) the cables.

Upon a quick glance, your monitor should support both DP 1.2 & HDMI 2.0, which both allow 4K@60Hz. Your Mac Mini M1 supports 4K@60Hz over HDMI 2.0 or USB C as well.

30Hz is pretty bad, haven't you noticed the mouse cursor being so jerky?

Sub‑par cables might explain the wonkiness in your KVM as well, potentially. Or given their "Engrish" description, it might be just a shite KVM and shite cables

Both. All. Anything in the chain that could be the weakest link, not supporting HDMI 2.0. And unlike analog "fancy" audiophile cables, with digital the cables' certification or version does actually matter.

Thanks again Frank. I guess I have just got used to the 30Hz. I am not such a heavy user of my home computer set up but it's good to know that there is scope to optimise it for the sake of a cable. I'll try one direct HDMI 2.0 and see if the frequency changes, then take things from there. 

An update to this - I have found that the issue is compounded by the USB-C power and comms plug running to the laptop "dock", has become quite finicky and doesn't always give a complete connection! Can't see anything physically "wrong" with it - no strain or physical damage - but it's not helping. Aside from that, the KVM remains frustrating in an ever-increasing variety of scenarios. I'll get that one from Currys and hope for the best. 

Thanks everyone for all the INPUT  

Received the ATEN one. Hooked it up, so far so good, everything connected instantly without reboots required, and as it has its own hardwired cables to go to the USB and HDMI outputs from each computer, I assume this is "better" than using my generic ones as these should be quality-controlled at manufacture. I also like that the switch is on an "outboard" cable so the snake's wedding of other cables can be put out of the way somewhat. 

What's the Hz display setting on the Mac say, out of curiosity? Since you had previously run at 30Hz

Direct or through the KVM, obviously!

Glad that it at least seems to work out for you now, of course.

This is already failing me! Tested it as described on Friday, with laptop and Mac connected. Disconnected laptop for the weekend. Mac working fine. Reconnecting laptop this morning, took a few minutes for it to pick up the keyboard and mouse, and now I have no communication to my monitor from either computer, via the KVM.

Additionally, since this attempted connection (where there IS some communication as the keyboard and mouse are working), my work laptop has gone a bit HAL 9000. Refuses to read from external HDD (after I finally gained company permission to WRITE to external HDD - this permission is removed quarterly and I have to renew the "exception"), Powerpoint has become unco-operative, and the thing refuses to shut down! :o Could it be related....?
Now that the laptop is not connected to the KVM, my Mac Mini has been picked up but only after a hard reboot. 


EDIT:

I have removed the laptop's docking station from the equation and the KVM seems functional again. I had suspected this of possibly being a weak link. I can use the dock in my lab/office (I am a mix of work-from-home and work-in-a-lab/office), it means that when I connect and disconnect the laptop at home I have to plug in a power cable, USB to the KVM and the HDMI, rather than just one "magic" USB-C but if this is the price I have to pay to have something working, it's acceptable. 
It's 2025. These things should just work!

And another issue! Switching from laptop to Mac seems impossible, this is partly due to the Mac Mini taking a LONG time to respond to be woken up from sleep mode - I had found this issue already long before involving the laptop, when it was just the Mac connected directly - a mouse click or keyboard press would be followed by around 15-20 seconds before the screen responded. Now when I switch from laptop to Mac via KVM, the monitor gives up after around 5 seconds and says there is no signal into HDMI1, and goes into hibernation, necessitating me reaching across and pressing its power button. But even then, after I've smacked a load of keys and waited patiently, it still refuses to acknowledge to Mac. It will happily switch back to the laptop. This seems to be an issue re: my Mac Mini and my monitor, rather than the KVM. I have set the monitor timeout to 100 seconds but it still give up and reports no input after far less than this, I assume that timeout is for something else. 
I might just have to accept that for whatever reason, this is never going to work consistently with my set up. I imagine that rebooting my Mac will make it work but I shouldn't have to be doing this. The KVM is creating more faff than it saves, I'll be better off with two direct KVM connections and two separate keyboards and mice, and switching the HDMI input using the switch on the back of the monitor each time (hitting some Mac keys in advance of this). What a mess!

I currently have two desktop PCs (one linux and one Windows) sharing one monitor/keyboard/mouse. My monitor has two inputs, one DP and one HDMI. So one PC is connected via DP and one via HDMI. I usually only have one PC active at a time with the other either sleeping or off. The monitor automatically selects whichever input is active. I can manually select which input it uses if both are active.

My keyboard and mouse plug into a usb hub that has two outputs and a button on top that toggles between the outputs. 

I think your monitor might be a bit smarter than mine! I feel that I need to coax / strongarm mine into displaying the desired input!

Any possibility to remote desktop to your win laptop from the mac? While not exactly ideal, it might sidestep your HW issues.

Rather than a KVM switch I just use a wireless keyboard (Logi) and trackball (cheapo Chinese) that themselves switch, and just plug the monitor (USB) back and forth.  The monitor does have multiple HDMIs as well but the switching is clunky.

Continuing this slightly hilarious* and much ongoing tech support thread, could be two reasons for that. Either the monitor is crappy and doesn't sense properly when the mac wakes up (had that with a certain Dell monitor, they finally had to ship me a new one with a newer firmware revision), or something in your mac's config messes up waking. Try connecting direct, let it sleep properly, then wake it up and turn the monitor on and off before the 20 seconds elapse. Or even power cycle it at the socket. 

For the second, you'd have to delve more deeply into pmset -g debugging, which is not exactly in the scope of this thread.

*: not very hilarious for you, I am sure – good luck!

Actually it's reasonably hilarious to me. 
Overall we do actually have a net improvement albeit one that might have been achievable with the previous unit. 
As long as I fully disconnect the Dell laptop, the Mac Mini will get picked up. This is workable because I am not constantly switching between the two. If the Dell is connected, then I am working. If I am not working, I disconnect the Dell and put it on a shelf (and then can switch to the Mac) without having to touch keyboard or mouse connections or the monitor (which has a clunky interface for switching to the monitor)

Thanks for your ideas, to be honest through my own laziness / apathy I may not get around to trying them all before this thread gets archived, so please don't think me rude for not describing outcomes for all of them. 60Hz is now available on a dropdown using the Mac (through the KVM) but I just tested it now and it caused the screen to go blank; a mouse-wheel scroll would bring it back for 1 second at a time before going black again, giving me a fun game of "navigate back to the display settings and get back to 60Hz". Damn you for mentioning the mouse cursor being jerky, I hadn't noticed before, but now I can see that it is! I will live with it, if I can't get 60Hz. Videos look ok to me. 


EDIT. I just connected the Mac HDMI direct to the monitor to properly evaluate the difference between 60Hz and 30Hz re: mouse pointer. It's slightly smoother at 60 (but still a tiny bit of lag). The difference isn't enough to make me want to keep the direct connections, as it's too faffy to change the monitor input settings (one of those naff little joystick menu switches on the rear, and the monitor is far enough back - on a nice wall mount - that I have to really stretch to get to the switch)

I imagine there will be security issues with this (my Windows laptop is work-issue and there are loads of 2FA logins, I have to apply for permissions to install things, I have to renew every three months my own admin authority to be able to write to external USB/HDD etc)