iPhone won’t accept WiFi password

iPhone X running is 12.1.1

wifi connection dropped

cannot connect to any network even with the password re-entered manually. Password confirmed and correct.

iPad connects to the same network without issues.

Last several days this has been a recurring issue. After a while the connection reestablishes itself automatically. And then at random times the problem comes back.

Any ideas on the cause?

tried rebooting the iPhone. Tried resetting the network settings in the iPhone. No change. Problem is still not fixed.

Since the other devices on the network network are not affected I can confirm that the issue is not the router.