Sorry to sound obvious, but have you selected the hard wired option from the network settings menu? Also, have you tested the ethernet connection with another device to convince yourself that it is working? Worth doing this as a process of elimination.
You also say that the TV itself used to cut in and out, was it turning off, then on again? This maybe a main board issue with the TV, and COULD be connected with the problem of the internet connection. But you do say this has rectified itself now.
Let us know how you get on!
K.