Follow up. To get my trusty old Mid 2010 Mac Book Pro (runs like a champ still after replacing batteries BTW) on some level of reliable WiFi connectivity, I purchased a TP-Link Nano USB WiFi adapter...

@LeeYan I am having this same 6+ months long issues with the Archer AX-55 as well. Done all the necessary steps - made sure in router mode not AP, updated to most recent firmware, tried various...