about R550 ５G

[masaki_matsumur]

Only 5G is unstable, connection is lost or SSID is not visible

Does it stabilize if I leave it for a while after installation?

[fredrik_kenmo]

That seems to be what we are seeing as well. 5G connections are more susceptible to problem and always reported as having poor signal strength in WebUI. I have a few other oddities left to isolate and/or explain - one being that when the devices loose connectivity I can reconnect to another SSID (same AP) and (sometimes) regain connectivity. That separate SSID currently use WPA3, whereas the first use WPA2 - connecting devices has been refreshed in part due to issue we are seeing. Regaining connectivity to the original SSID won't work without fiddling - no clear idea as to repeatable steps to recovery. Have you made any changes that you believe has help alleviate the issues at hand? I have currently disabled wifi6, set TX power to max and use ofdm-only. 

[masaki_matsumur]

I don't have a good idea for a solution. I'm going to try adding a stock AC power supply.

[masaki_matsumur]

I replaced the unit but that didn't solve the problem, I don't understand why it's only 5G.

[masaki_matsumur]

Does DFS（Dynamic Frequency Selection） have anything to do with it?

[velosol]

DFS is there to prevent interference with other users of the spectrum (not WiFi, radar and such) and the AP must change channels if it detects those users but that would only explain the AP choosing a different channel.