Trouble getting online, some sites not loading

Hello all,
I'm having trouble getting online on my Comcast modem/router combo device.

I've tried disabling IPv6 in Windows, no change. I've flushed dns, released IPv4, renewed IPv4, no change. I've power cycled all network devices (router/modem, powerline adapters), no change. I've even changed the adapter settings to use 8.8.8.8 as primary DNS and 8.8.4.4 as fallback DNS then flushed DNS, no change.

Google and YouTube seem to work fine, certain sites don't load though. Discord and Psyonix don't load at all, many more are also not loading.

I'm not sure where the issue lies. Any help is appreciated.