U2725QE, MacBook ProMax M1, Ethernet does not reconnect when switching source back to MacBook

i have a MacBook M1 max and the dell u2725qe monitor connected by the thunderbolt 4 cable. Ethernet is connected on the monitor and used by the mac. 

the monitor has been updated to the latest firmware of M2T102. 

the issue I have is the Ethernet disconnects when I switch back from another source, in my case my desktop pc. Before switching from the mac to the pc source the Ethernet connection is fine and running at 2.5gbps, the switch to the pc establishes a connection when switched. 

This happens when switching away from my Mac on the thunderbolt input to another input. When switching back to the Mac on the thunderbolt connection the ethernet is disconnected and DOES NOT reconnect. The only way to reconnect the ethernet is to unplug and replug the thunderbolt cable, which for me is not a workable solution nor as advertised.

I have tried different thunderbolt cables including a new supplied DELL one, an Apple Mac thunderbolt 4 cable. I have even tried with another MacBook Pro laptop - all with the same issue.

The issue can even be repeated by just turning off the power to the monitor and turning it back on. The same result of the ethernet not reconnecting happens.

Interestingly when I used a thunderbolt 3 cable the monitor performs as expected, whereby switching inputs or turning off the monitor and back on again the ethernet automatically reconnects correctly. However a thunderbolt 3 cable does not give the full advertised functionality of the thunderbolt 4 cable, slower network speeds, power delivery etc.

Additionally and interestingly when i turn on (or off) MST the ethernet DOES reconnect on the macBook. I assume this is because the monitor is going through a power cycle and reestablishes all connected devices.

I have been in discussions with DELL tech support and TBH its become a bit of a farce.

My assumption is the software/firmware for the monitor is still not correct for macOS on thunderbolt 4.

is anyone else having this issue?