Have to disconnect wired ethernet router connection to boot up

On my Dell Studio 17 laptop I have recently adopted Fibre broadband. On BT advice I have switched to a wired connection instead of, as previously, wireless. This almost doubles the DL speed, which is great, BUT I know find that when I switch on and attempt a boot up it hangs and will not proceed. If I remove the wired connection, all is fine and then once the cable is plugged in again all is fine. But as this happens every time I switch on in the morning, obviously there is something wrong. 

Am I missing something

OS Windows 10