ZHA setup runs into generic aiohttp.server error - need help

Hi,
I’m struggling to setup ZHA and hope someone can point me in the right direction. I have a HA OS setup on a Pi4, with two Skyconnect dongles attached to it; one I use for Thread/Matter, the other one I just added for Zigbee support (to avoid any multiprotocol issues).

Now, when adding the ZHA integration, I get to select the Zigbee radio (the Skyconnect), am asked about the Network formation, and then, after about 10 seconds, always run into a very generic error:

image

Home Assistant Core logs show that the issue is with aiohttp.server:

Logger: aiohttp.server
Source: runner.py:189
First occurred: 26 November 2024 at 08:40:44 (2 occurrences)
Last logged: 07:49:52

Error handling request

I keep trying to troubleshoot and fix this, looked into my http/https settings (I’m using nabu casa for remote access, so all is pretty “simple” - no nginx, let’s encrypt stuff). But I’m really at a loss how to configure (or even wipe some legacy configuration that may be lingering in my setup).

Any advice?