For weeks I could not get Youtube to work on my iPad. I thought it was the iPad. I changed the DNS servers, I rebooted, reset, you name it, I then took it to my beach condo with Verizon DSL and I could play the Youtube videos fine.
Came home, and had the same problem with my PC. I thought it was the router. Checked that and I could not find an issue. I don't have a Verizon router, I use a Cisco router hooked up to the the ethernet connect in the ONT. So I unplugged the router and plugged my PC into the ONT using the ethernet connection. No Youtube. Same issue.
I fixed it by releasing the Verizon IP address on the router, unplugging the router from the ONT, waiting about an hour and then replugging and getting a new IP address.
Verizon must be blocking selective IP addresses.
