Intel I225-LMvP Ethernet in Tunderbolt Dock not working properly

[droidben]

I have a Dell XPS17 9720 which has TB4 ports all around. It has Ubuntu 22.04 with latest packages.
This I used to connect to a ThinkPad Thunderbolt 3 gen2 dock from Lenovo, this worked perfectly, other than that I wanted 2* 4k60 screen instead of 4k60+4k30 screens.

So I bought the ThinkPad TB4 Dock, which seemingly has a Intel I225 chipset inside, though limited to gigabit it seems. In Linux this is detected via lspci but when enabled no IP-address is pulled from my dhcp. dhclient -r would not help either.

$ lspci | grep -i ethernet
0000:2b:00.0 Ethernet controller: Intel Corporation Ethernet Controller (2) I225-LMvP (rev 01)

I have updated the Dock to latest firmwares.

A quick research tells me that the I225 should be supported by Ubuntu 22.04.

What next steps can I do to troubleshoot this unwilling ethernet controller?

[droidben]

Update:

The issue has been (partially, see below) resolved by buying a Caldigit TS4.

Next problem: the TS4 has the same Ethernet controller as the ThinkPad TB4 Dock, though with full 2.5GBase-T support… When it works. It’s about a 50:50 chance the Ethernet controller is detected when the dock is connected.
Sometimes only a reconnect solves the issue, other times a full reboot and power removal and reconnect of the dock is needed.

It seems I have set foot into a very much beta situation with the TB4 support on Linux. I will possibly update on this thread once the situation changes.

Edit: the I225-LMvP controller is the same except for the TS4 having the newer revision controller:

$ lspci | grep -i ethernet
0000:55:00.0 Ethernet controller: Intel Corporation Ethernet Controller (2) I225-LMvP (rev 03)