Weird Disconnect issue tonight

In general, this sort of thing is an ISP level problem. A regional router is down, one of your ISP's peering agreements has gotten misconfigured, someone is attempting a DDoS and the fallout is choking other traffic, fiber backbone got cut with a backhoe, etc.

If your ISP doesn't block it, the traceroute (tracert in Windows) command is your best troubleshooting tool, although using it well takes some practice. Trace routes to various reachable and non-reachable sites, and try and identify the common factors on the non-reachable ones.

There's also some chance you've been infected with some sort of virus or malware. In their efforts to redirect you to corrupt sites and prevent you from visiting anti-virus sites, they can screw up your ability to use the Internet properly. It's probably a good idea to run a full scan with a different product than you usually use, such as Malwarebytes and CCleaner.

If you're less technically inclined but have time to spare, you can try calling your ISP's technical support. Have a list of places you can't reach, preferably with their exact names if not IP addresses. Be polite, but very specific that you can get *most* places, but not *these* places.