Hey! @cholla thanks for the info now I have configured the router and pc on same mtu and all tests are running fine.
@Kiwegapawa I am really not understanding what's happening with you. Is your isp stealing your bandwidth? Are you not getting the speed which the isp promised all the time? Or is your isp keeping eye on your data?
All I can say is use vpn if you think that they are doing some malicious activities. Also if speed is varying you should contact your isp regarding that and ask them for stable connection.