Re: [Hampshire] [OT] More IT than Linux: Bizarre KVM issue.

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Author: Dom Rodriguez/shymega via Hampshire
To: rmluglist2, 'Hampshire LUG Discussion List'
CC: Dom Rodriguez/shymega
Subject: Re: [Hampshire] [OT] More IT than Linux: Bizarre KVM issue.
Hi Rob,

Glad to hear it's sorted. Would definitely be grateful for the link as an interim option.


On Mon, May 23, 2022, at 7:51 AM, rmluglist2@??? wrote:
> Hi Dom
> I'll dig the link out but, fwiw, I finally sorted this out - and it's
> not a KVM issue. It's actually to do with USB and particularly the
> way in which USB is "serviced" by Windows. As I said in the OP, I'd
> not come across these errors on Linux or Mac.
> Suffice to say, if you're having the same problems I was (occasional
> mouse and or keyboard freeze, then keyboard repeating for no reason),
> the answer is delightfully low tech: change the USB port until you find
> one that works. My new work laptop (HP Elitebook) exhibited the same
> problems as my own Windows machines. My KVM was connected to the work
> laptop via a spare USB A port and was showing the errors above. I
> moved the KVM to a USB C port on the laptop (via a tiny A to C adaptor)
> and it's been solid every since - over 3 weeks now.
> I did some reading into this - though I've lost the link now. It
> turns out Windows does not treat all USB ports equally (and it's not to
> do with USB 2 or 3 etc). A lot (apparently) depends on the order in
> which the ports are serviced by Windows. It _seems_ (YMMV) that USB C
> (being far more popular nowadays) is handled before USB A ports.
> This, of course, didn't explain the issue on my home PC (which doesn't
> have USB C) but changing the USB port on that has fixed that too.
> As I say, YMMV, but changing the port does seem to be the workaround.
> Thanks
> Rob
> -----Original Message-----
> From: Hampshire <hampshire-bounces@???> On Behalf Of Dom
> Rodriguez/shymega via Hampshire
> Sent: 22 May 2022 16:52
> To: 'Peter Alefounder' <hampshire@???>
> Cc: Dom Rodriguez/shymega <shymega@???>
> Subject: Re: [Hampshire] [OT] More IT than Linux: Bizarre KVM issue.
> Hi,
> I have a cheap DP KVM switch, which is a bit unreliable. I don't have
> any DVI devices anymore! 😃
> I do work on Input Leap, a fork of Barrier KVM switch software (itself
> a fork of Synergy 1.x), but I've moved my focus to my own hybrid h/w /
> s/w KVM switch, called Continuity. The only problem so far is that the
> idea was for video streaming, and for work laptops, it needs a driver.
> I haven't written the USB or video streaming drivers yet. No experience
> with Windows or macOS kernels...
> Can you link to the 8-port KVM switch? I'm running out of ports on my
> 4-port KVM switch, and with the work laptop now, I need an extra port!
> Onto your issue, the only thing I tend to experience is USB bus
> malfunctions. Generally, it recovers after I turn off the USB hub and
> on again after switching...
> Thanks.
> On Thu, May 5, 2022, at 11:40 AM, rmluglist2--- via Hampshire wrote:
>> Hi all
>> Has anyone had an issue with a KVM where there’s a distinct lag and
>> then key repeat problem on some of the boxes and not others?
>> I have a 4 port (Belkin USB / DVI) KVM switch. Two machines are
>> Windows 10 (on which this problem is intermittent) and the other 2
>> machines are a Mac and a Linux (Fedora) box. On the non-Windows
>> machines, the issue doesn’t exist.
>> I’ve tried connecting the kbd straight into the windows machines and
>> that fixes the problem. Then when I revert to connecting via the kvm,
>> the problem is intermittent i.e. happens about 5%-10% of the time. As
>> such, while this would point toward a faulty KVM, why is this only
>> occurring on Windows machines? I’ve checked Device manager and the
>> same device is detected whether via the kvm or directly connected.
>> As I say, I’m loathe to change the kvm because a) they’re expensive
>> and I’d actually have to replace the 4 port with an 8-port which is £180:
>> very pricy for me. And b) Linux and Mac have no problems. I could
>> replace the 4 port with another 4 port but I have been looking to
>> expand connections for ages.
>> And c) I realise I could drop Windows altogether but one’s provided by
>> my employer – so that has to be Windows
>> Any thoughts anyone?
>> Cheers
>> rob
>> --
>> Please post to: Hampshire@??? Web Interface:
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> --
> Kind regards,
> --
> Dom Rodriguez (also known as shymega)
> --
> This email has been checked for viruses by AVG.
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> Please post to: Hampshire@???
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Kind regards,
Dom Rodriguez (also known as shymega)

Please post to: Hampshire@???
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