When I look at the settings on my phone I see it is connected to the 5GHz side of the router which is set at channel 153 (??)). The other 2.4 GHz is set to auto and has a possibility of up to channel 11. My phone currently seems to be connected with an IP4 address which is what both the router show, and it is working just fine. At the bottom of the settings screen it also shows some IP6 addresses but the router does not show them.
I am watching to see how things go after I recently made a router change. Combing through the router settings I noticed that the IP6 internet interface was disabled. I tried several things to enable that interface and found that the 6to4 tunneling path would auto-configure and that turned on the IP6 internet interface. My private network devices all communicate with each other with IP6 but apparently know to use IP4 to go to the internet if the IP6 path is not available. I am guessing that the phone does not have that capability.
My current hypothesis is that perhaps the phone connected with IP6 to the router which did not have an active path to the internet. If it connected with IP4 then it did have a path and everything worked correctly. Since the problem with connectivity is relatively recent I am wondering if a router upgrade or phone upgrade or windows upgrade changed things which caused the problem. Are you aware if any phone changes in this area? That is why I asked if there was a preference in the phone software to choose IP4 vs IP6.
I have only 2 or 3 occasions since I made the change to observe phone behavior but so far things have worked they way they should. I will post again after I have had more occasions to check.