My wired keyboard suddenly started to randomly disconnect

**Background: **two weeks ago we upgraded to a brand new mesh router. One of the mesh devices was placed in my room and plugged via ethernet to my PC. After setting everything up I started my PC to test out the new connection but after only a few minutes the background lights on my keyboard went out and the keys stopped working. Immediately I took out the keyboards USB cable and plugged it back in and swapped USB ports on the Pc but while the windows "device connected/disconnected" sound played nothing happened and the keyboard remained non-functional. I then restarted my PC and it detected the keyboard again and it worked perfectly for the rest of the evening so I just thought I had fatfingered some weird shortcut and thought that'd be the end of it.The problem however returned the very next day after this first "fix". I removed the ethernet cable thinking that might be the issue but it happened again a few minutes later.

The problem: the lights on the keyboard goes out and it stops registering button presses. Whatever buttons where down when it happens seem to still be "held in" but nothing new will register.

**Cause: **as far as I can tell there seems to be no obvious logic as to why or when it happens, sometimes it happened after only a few minutes and other times like this week I went Monday to Friday using it like usual without it failing once. It has happened both when idle on desktop, watching YouTube on chrome and when playing several different games. I didn't install anything new before it started and while a few things updated in the days before they aren't small unknown apps but rather Discord, Chrome, Origin and the likes. I've tried to search for others with the same problem but haven't found anything that looks like exactly the same. I did find a few that seemed somewhat similar and I have tried those fixes but they've not worked. I left the pc on for 10 hours in safe mode on Monday and nothing happened and although that could just be luck as it happens so infrequently it is at least something.

**Attempted fixes: **I've changed the keyboards USB cable (A to C), tried other USB ports both next to eachother and on other parts of the chassis, tried to see if I was doing anything particular when it was disconnecting, unplugged the ethernet cable to run on wireless like before this all started, disabled the wireless adapter to run on wired, reinstalled/updated a bunch of drivers, removed overclocks and reset Bios settings to default, ran virus checks, unplugged all extra USB ports from the motherboard, uninstalled all USB devices and the keyboard from device manager, made sure no power saving stuff was active, wiped keyboards on-board memory settings, repaired pc registry with sfc /scannow and did a DISM scan, nothing of which seems to have done anything. I have left the pc on for about 10 hours hours in safe mode without any problems which is at least something to go off. I've tried my mk850 keyboard on another PC and an old dell keyboard on my PC and they've worked perfectly. Using the dell keyboard on my pc even worked while my main keyboard had died and was still connected and unusable.

Other: The only places where the pc even acts as if something is wrong that I've found is in device manager where the keyboard flip-flops between normal status and that it had been removed despite still being plugged in (error 45). Devices and Printers acts similarly.

The only other real clue I have is some really weird stuff is going on when restarting. If I use the restart button in Windows after the keyboard has died I get a failure to boot with a "black screen with 99 in corner" error which earlier posts seems to say is a some motherboard I/O failure or completely dead motherboard. The thing is that most of these posts are about new builds where the pc doesn't even boot, for me it only happens after restarting when the keyboard has died. The most common consensus on this is that the motherboard is dead but mine is obviously not, at least not completely. I've tried the suggested fixes anyway but nothing worked. The only way out of this 99 error is to use either the power or reset button on the case. If I use the case restart I will boot into Windows normally but the keyboard still won't work and I will have to shut down the pc completely before powering up again. After shutting down completely the keyboard always works again without any problems.

Using the case restart button after the keyboard dies instead of the windows restart is the same except the error is 9c instead which seems to be pointing towards something USB related. A lot of posts say that it is boot order related but I've checked the settings and everything seems fine and none of the suggested fixes worked either.

Restarting before keyboard failure works just as it should with no problems at all so they definitely seem to be related but I don't know which is the cause and which is the result.

Any help at all would be very much appreciated and I'd be happy to provide more information and tests if you need.

Windows 10 home 10.0, build 19041 Cooler master mk850 keyboard Logitech g400s mouse Msi Z87-g45 motherboard on BIOS Version 1.9 Intel I7 4770k @3.5GHz 2x8Gb Kingston HyperX fury ddr3 @1333MHz ram Asus ROG strix GTX 1070 Asus ac68 wireless adapter (disabled in device manager) 750w Psu