U2422HE, switch video input, PC doesn't wake up

Question

I have bought a Dell U2422HE and I have two laptops connected to it.

- 1st laptop is connected via a DP and a Type-A/B USB link (upstream USB ports)

- 2nd laptop is connected via the USB Type-C link.

- A combo of USB mouse and keyboard is plugged to 1 of downstream USB ports of monitor (USB upstream port is mapped to corresponding source input).

I have it setup correctly, when I change the video input, the active USB upstream link also changes, so it automatically change the input carries over the keyboard and mouse that are connected to the monitor via USB downstream port.

----- But there is a problem here as a practical situation:----

- When I am using 1st laptop, then it goes to sleep mode (as OS power plan or manually), I can wake it up with mouse or keyboard (as long as video input not switched). But, if I switch to 2nd laptop, then I switch back to 1st laptop (that time it went to sleep mode) then I cannot wake the 1st laptop up. It seems that there is no USB signal switchover together when video input has no signal .

- Same situation with 2nd laptop (can eliminate the USB port type/protocol).

----------------------------------------------------------------------------------

I can see one similar post with different monitor model U4919DW 1 year ago but not solved yet.

Conclusion: if the display link goes to sleep on either of the laptop, changing the video inputs means the U2422HE does not get a video link. In that case it apparently doesn't do a ('forced') USB link switchover. Since I effectively don't have a mouse and keyboard connected to the laptop, I can't 'wake' it. Which means I don't get a video link and thus of course I also don't get a USB link. The USB link stays with the previous video input PC.

Is there a way to set the U2422HE to forcefully switch over the USB link, even if it doesn't find a video link on the selected video input?

Does anyone have experience on this? Please kindly support to solve it. Thank you.

Regards,

Ryan N

DELL-Nat M · Answer

Reposting the solution since its in a different thread:

* Turn the P2720DC and Latitude 7480 off
* Disconnect every cable (including power) and USB device from the P2720DC
* Press and hold the P2720DC power button for 8 seconds

* Plug the AC power adapter into the Latitude 7480 power port
* Open the lid and turn the Latitude 7480 on

* Reconnect the power cable to the P2720DC
* Reconnect the P2720DC USB Type-C to C cable to the Latitude 7480 DisplayPort over USB Type-C port
* Connect the other end of P2720DC USB Type-C to C cable to the P2720DC USB Type-C port
* Turn the P2720DC on
* On the Latitude 7480 keyboard, press Fn+ F8. Does the Windows desktop appear on the P2720DC?

XPS_Man · Answer

Interesting !!!!!!!!!

So USB Upstream port is linked to the selected INPUT on monitor. I never though about it as I use a single computer with this monitor.

So obviously if the machine is in sleep, means Monitor is not getting any video signals from computer so USB upstream is also disconnected. I think this is a Bad design choice Dell. Since there is only a single upstream on monitor, obviously a user will have only one computer connected to USB upstream port. So its senseless for Dell to link it with selected port. It should act like USB Hub leaving it linked all the time regardless of selected input on monitor.

BRO i can only recommend disabling sleep on laptop 1

Ryan_Nguyen · Answer

It's quite weird. Because it's not 100% happening like your point "So obviously if the machine is in sleep, means Monitor is not getting any video signals from computer so USB upstream is also disconnected". I can still wake up a laptop which is sleeping via mouse/kb as long as don't change video input source of Monitor, only after I had changed the source and rolled back couldn't I wake that sleeping laptop anymore.

Dell service team is working on this case, however their gathering question is further and further away the core issues, lol.

Maybe this is a limitation of product in term of KVM controlling.

Anyway, tks for your recommendation.

Ryan_Nguyen · Answer

Total agree with you, I hope Dell find out the root cause which may come from KVM controller.

They can easily replicate the situation and give feedback rather than chasing with far away information.

I'm also facing same problem and mentioned in another post: https://www.dell.com/community/Monitors/U2422HE-switch-video-input-PC-doesn-t-wake-up/m-p/8013381#M136505

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U2422HE, switch video input, PC doesn't wake up

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