You’d better contact support with this and follow a number of their instructions. They have a procedure to test the connection speed with our servers in different regions. The point may be in the heterogeneity of the network - up to some servers you have a high connection speed, to others it is worse. It is rather inappropriate to say “everything is fine with other sites”, you probably opened every site on the network and checked the connection speed? If your YouTube is working well, that doesn’t mean anything, these guys have spent hundreds of millions of dollars on infrastructure. Unfortunately, we do not earn that much yet.