I can not connect my iPhone 10XR to the router. After I forget the network, etc. it sees it for literally 1 second and then disappears. It sees the 2.4 and 5G and I can choose it in settings. My iPhone software is updated to the latest version.

I have chatted with support and had issues with my daughter's Chromebook, but that was resolved. Luckily I have unlimited so I connect to the internet that way, but I have no idea why my iPhone won't connect. It connects to other routers and to the internet. 

Support had no idea why it isn't connecting to the internet thru the router, so I'm curious if anyone else had the same issue.

Thanks!