Wifi Disconnect while HDMI is connected

We have also suffered this issue with 3 of our Latitude 7410 laptops. Consistently, they drop WiFi connectivity when plugged directly into an HDMI monitor.

This issue needs resolving by Dell.

The fix noted in this article does work (albeit, we had to completely disable the n/ac/ax function), which utterly cripples WiFi performance. With monitor not connected and WiFi card properties left as default, speed tests show solid 200Mbit in both directions. With the n/ac/ax modes disabled, maximum of 20Mbit in both directions, so this is an unacceptable fix.

Does anyone have any Dell reference numbers that you're happy to provide me with for when I have our team log the issue with Dell?

For those that are interested, we managed to resolve our issues on the Latitude 7410 laptops by installing at least v1.7.0 of the BIOS firmware. Any laptops that were on v1.5.0 were affected but I can't speak for any versions in between v1.5.0 and v1.7.0 as we didn't have any in our estate.

No WiFi adapter modifications were necessary after the BIOS update.

I can't speak for the other hardware models though, I'm afraid.

Whilst my Precision 5560 has all BIOS and driver updates at time of writing, the issue persisted. 

Following the suggestion to set 802.11n mode, the issue stopped, and I was finally able to use WiFi simultaneously with an external monitor via HDMI type-C cable. 

I had arrived at the promised land.

I have experienced similar issues with bluetooth devices in the past where I must connect to WiFi via 5Ghz connection so that it doesn't drop out over 2.4Ghz when I connect a bluetooth speaker that also operates via 2.4Ghz. So it makes sense to me that a cable acting like a giant transmitter could be emitting a frequency to rival my puny WiFi antenna. Thus being able to set WiFi frequency to move out of the cable's range is a good call. 

Superior shielding for an HDMI cable might also help especially if wanting to retain the other WiFi modes, but I'm guessing even some high-end cables will still interfere. It begs the question: aren't all the standards and quality engineering from DELL supposed to navigate us through all this subjectivity?

Since my BIOS is 1.12.0 I wonder if there has been some regression, since other users here had reported a fix with some BIOS versions.

Addendum

BIOS 1.13.0 also exhibits this behaviour,

802.11n mode is my only saviour.

I couldn't get it to work so I just purchased the user a $20 TP link USB wifi adapter and it's been find. I'd like to get it fixed permanently but doesn't seem like it's possible

Hey bro, 2023 here haha

I have a Dell Precision and I bought a RadioShack HDMI cable... and this cable was injecting somehow interference into my Laptop

I just got another generic HDMI cable from another small store and connected it into my laptop and I no longer have issues

I kinda think the problem could be that RadioShack HDMI cable is unshielded (im guessing) and this cheap street market cable is shielded and that's why I'm having no issues. Maybe this interference is being injected into the motherboard and affecting, somehow the WiFi card