Are your WiFi devices actually dropping every 5 seconds, or are you just worried about WiFiman readings?
If it’s just WiFiman, you seem to be extremely close to the router at -30 dBm, like touching it. Try backing off a little.
If devices are dropping, try plugging the ASUS into a different power outlet, or better yet, a UPS outlet if you have one. Try not using a power strip if you are plugging into one.
If somehow available, try a different power cord for the ASUS.
As a longer-shot, reflash the latest firmware again, or try Merlin Firmware if your ASUS model supports it.
I think I was in the next room over for this snapshot.
It is losing wifi with a little exclamation mark on the phone by the signal bars.
The wifiman is only to see why it is losing signal and that is what it showed. The signal is gone, then back, than gone.
On my Android phone the exclamation point usually means there’s something wrong not with the WiFi but with the service it gets when connected to the WiFi, e.g. no working DHCP server or no working DNS server or no Internet connectivity. And if that is the issue then the “signal loss” you see may not be a problem with the router’s WiFi signal but instead might be the phone choosing to leave that network and look for another that provides working Internet service, reconnecting to try again when it finds no alternative.
To eliminate the WiFi as the issue try connecting something to an Ethernet port instead. If that fails to get Internet service and you fix what is causing that failure you’ll likely find the WiFi is fixed as well.