What could be causing the ERR_CONNECTION_TIMED_OUT error?

Question

Domain Name System

Recently some sites started responding with ERR_CONNECTION_TIMED_OUT error. I tried to log in from different browsers, from different devices within my local network. I tried to connect to the Internet directly without a router. The error still exists. The provider said that the problem is not on their side. Tracing problem sites shows that they are available, but they do not want to load.

What are the thoughts? Where should I dig?

update. It turned out that the provider was having problems with routing, and I'm the only one who "noticed" this. The question is closed.

Answer 1

I would start with this:
Disable antivirus
Disable firewall
Disable proxy Disable
router.
Run from command line:

ipconfig /flushdns
ipconfig /registerdns
ipconfig /release
ipconfig /renew
netsh winsock reset

In DNS, register 8.8.8.8 and 8.8.4.4
OR
In DNS, register automatic receipt.
Set IP manually from the address range of your mesh
OR
Assign IP automatically
Next - according to the results. And by the way, what does tracert show?