As you can see from the title, I have narrowed down to my router that it is not letting my PC load YouTube thumbnails and other (seemingly random) CSS elements. The problem persists no matter if my connection is wired or wireless to the router, but goes away if I connect directly to the modem or another network. I've tried resetting the router, but that doesn't help either. The weirdest thing is that it only affects my PC. I'm just completely perplexed about what the cause is or what to do. Thx in advance.
Figured it out. My Windows Defender Firewall was not allowing the app to communicate on any networks completely and yesterday the dialogue box popped up for it and now I can go into the Windows Defender Firewall settings to allow the apps that I want.
Do you have the DNS server overridden in the router config? Probably connecting directly to the modem would avoid that. Have you tried turning on the developer tools (Firefox has them) in the browser. That might allow you to see if there is something common in the errors.
That was a good call on the developer tools in Firefox. It seems that whatever is not showing is coming from an unsecured connection, such as i.ytimg.com or [removed].com . Any ideas on what to change in my PC's or router's config?