I also tried to set 1000Mbps Full Duplex instead of Auto Negotiation in settings, but it did not help. If I put my old Huawei router between C7 and ISP, I get the full 200M speed from C7. This means...

My ISP provides 200M speed. If I connect computer directly (ethernet) to my ISP-connection, I get the full 200M. But if I connect to Archer C7 Ethernet LAN I only get approx 94M. I had the same...