Cudy WR1300 v1 bridge broken after 23.05.6

Describe the bug

After upgrading from 23.05 to 24.10.2 (or else to today's snapshot) networking breaks.
With some work I managed to access the AP with SSH using a link local address and figured out that it failed to add other interfaces (both wired and wireless) to the bridge connected to the CPU interface (eth0).

OpenWrt version

?

OpenWrt release

24.10.2

OpenWrt target/subtarget

ramips/mt7621

Device

Cudy WR1300 v1

Image kind

Official downloaded image

Steps to reproduce

I tried upgrading from 23.05.*, first to 24.10.2 and after that to today's snapshot.
Downgrading back to 23.05.6 (r24232-539228933c) made everything work again.

Actual behaviour

Networking is broken because only the CPU interface eth0 is connected to the br-lan bridge.
The other interfaces work fine, but trying to manually add them to br-lan with the brctl command fails with:

brctl: bridge test: Invalid argument

The opposite is true as well: I created a new bridge and added all the other interfaces to it, but then trying to add eth0 (after removing it from br-lan) would fail with the same message.

This is not a user interface issue: I have verified all this from the command line.

Expected behaviour

No response

Additional info

No response

Diffconfig

Terms

• I am reporting an issue for OpenWrt, not an unsupported fork.

Start by reproducing the bridge failure on the Cudy WR1300 v1 with the ramips/mt7621 images, comparing 23.05.6 with 24.10.2 or the snapshot. Inspect the bridge configuration and the interfaces involved, including eth0 and br-lan; the issue is done when wired and wireless interfaces can be added to the CPU bridge without the reported Invalid argument error.