Can't log on to ring.com via my home router's public IP address

OK, odd problem. Recently I noticed that I was unable to log onto my ring.com account from my laptop. Kept getting an error saying my email or password was invalid. Couldn't log on from my phone, either, or from two other desktops in my house. Changed passwords, cleared cache, tried a different browser, rebooted my router, etc etc. This doesn't have anything to do with the app, I was trying to log on to ring.com from a browser on these devices. Then yesterday I noticed that if I turned off wifi on my phone and used cellular data, I could log on. Then I tried tethering my laptop to my phone (rather than using my home network) and again, I could log on. So....this led me to try again with the laptop, but using a vpn service to appear to ring.com as if I was at a different IP address. It worked. For some reason, any device that I use is unable to log on to ring.com when using the wan public IP address in my router (Frontier Communication is my ISP). Does ring.com have a blacklist of IP addresses that I somehow wound up on? Is there any way to further troubleshoot or otherwise correct the issue? Thanks for any help.