help me!! iphone won't stay connected to wifi

I have an iphone xs. woke up monday to find my phone had dropped the wifi.  rebooted the router. seemed to be fine then, however, i honestly didn't really check.  a few days later, i noticed it wasn't connected again.  

web search - tried the various suggestions (turn wifi on - off, turn airplane mode on - off, restart the phone, restart the router, reset wifi setting on the phone) and managed to stay connected long enough last night to download the latest ios.

all have failed! i am starting here, hoping to find someone who has figured out what the problem is, before moving on to iphone help and carrier help.

everything else in the house seems to be working just fine.