Apple TV HD no internet despite wifi connected since update to TvOS 15.5.1(19L580). All other devices in house hold fine

Hi! I have an AppleTV HD (A1625) and up until a few weeks ago it was working perfectly! I went on vacation and when I came back, it just complains that there is no internet. I can see in settings that it has decent signal and is connected to the network. I can see in the router logs that the AppleTV is associating - however every app complains that there is no internet.

I have reset the apple tv and reset it up, and it worked... until the next start up and it has the same problem. I can get it to work for a session by forgetting the WiFi and reconnecting, but after it sleeps/restarts its broken again.

Every other device in my network is working perfectly, which eliminates the internet connection itself. I have 3 other Apple TVs in my house (Apple TV 3rd Generation - A1427) and these are all working just fine! In fact I replaced the A1625 with an A1427 and it works perfectly.

I am not 100% sure if it's an issue with the AppleTV or with the Router, however the timing of the issue aligns with the release of TvOS 15.5.1 on 25th May. As nothing has changed on the router side, my initial point of suspicion then is an issue introduced in 15.5.1.

My google-fu has not revealed much, though I can see that others have posted to Apple Discussions reporting similar issues recently (in the relevant time frame), though the description of the issues are not sufficient enough to say if they are the same. On the one hand this lends some further weight that an issue exists in the latest TvOS build, but also that it's only affecting a small number of users, so may be a specific combination of Apple TV + router model (I have an Asus RT-AX58U)

Some thing I need to look at

• I have swapped a 3rd gen in, but haven't tested the AppleTV HD in other locations in the house
• I have yet to test the AppleTV HD with ethernet instead of WiFi
• I need to dig deeper into the logs on the router, and perhaps even run Wireshark and see if the router (or apple tv) is initiating a dissociation for some reason

I will post this whilst I investigate the above in case someone else has the same issues and comes looking for a solution (we can then see if it's more people having the issue) or if someone has solved it already