Samsung Smart TV connectivity

I have a problem with only ONE of my Samsung Smart TVs connecting to my Netgear AC1900/C6300BD router. There are times when it connects and is usable. Other times I need to use the wired connection (using WiFi repeater) when the wireless fails. At times, even the "wired" connection won't work (since in reality, it's wireless, though the "smart" TV doesn't know that). Anyway...all other devices work, tablets, phones, computers, printers, etc. on wireless.

New problem last night...used wireless for Netflix, but picture quality was terrible, changing from clear HD quality to fuzzy 1960's color TV mode (yeah, I'm that old). I tried disconnecting from the wireless network and switched to "wired", and neither would connect to the router. So, I reset the router, and all was well.

To further muddy the waters, this TV/router combination worked fine before we moved from Mesa to Buckeye (wired cable -- Mesa, Optic Fiber -- Buckeye). Any suggestions? I've also tried to use a manually entered IP (vs. automatic)..and three extremely unsuccessful tries with Cox chat sessions.