My internet is typically just fine but when I try to use LAN it cuts in and out every few minutes, which as you can imagine ruins everything. Currently using wi-fi as my Ethernet port somehow has ceased working. No other computer wired or wireless in my house has this problem.

Please, can you just explain how the network is setup so that we can know where to help? Thanks.
Please explain clearly what you mean when you say, "use LAN" It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.***William Henley***
