Netgear XR500 does not work fast (intermittent connectivity issues) with Apple iPhone XS

I have a XR 500 that is running the latest firmware and has been factory reset. I am running into an issue with using Wi-Fi and iOS apps on my iPhone XS (4th one replaced since September). My connectivity for loading Facebook, Instagram, Spotify, Snapchat, and other related apps is slow/non-existent. Sometimes it loads fine then a few moments later, it cannot refresh the feed in which it times out or says I do not have internet connection. I am running AT&T U-Verse Gigabit fiber running in IP Passthrough/Bridge mode so my XR500 does all the work. This issue only happens on my iPhone XS while my PC, Mac, Androids run fine with no issue. I have also did network reset on iPhone along with factory restores and replacements. Apple thinks its my ISP (AT&T) or Router Manufacturer (Netgear). I have tried to modify channels for preventing antenna interference, changed DNS to Google and Cloudflare, and other tweaks. I am not sure what else to try to resolve the issue on my iPhone. I noticed that connecting to a VPN client/service improves the connection but still needs work. Does anyone have any suggestions? I have a video that I cannot attach but can send it to you with DropSend if you want to see what my issue is. Please let me know if you think there is something with my router or ISP's connection.

Thank you!

MAPE15