big porblem with my ea server connection

i wonder if someone could help me, my xbox doesnt seem to be keeping connected to the ea servers when it is wireless. it works perfectly when it is connected via the ethernet cable but ones i take my xbox into my room it has no problems connecting to the internet and it has been fine for about 3months then suddenly it started playing up. t says it is unable to download the latest update and when i do eventually get in a game it is just stop start stop start really really quickly, its a nightmare!! please could someone help