Xbox wont conect to internet?

I'm at a hotel and have been running my xbox through my mac with an ethernet and internet sharing just like at home and it was working great. i got back to the room tonight and it wouldnt connect. it told me to go above 1364 mtu which i already was, never had that problem before. now my mac and xbox are both saying that there is no cable plugged in and ive tried every combo of plugging and neither pick it up. the xbox picks up the cable for a moment when i restart my mac but thts it help plz. i have 7 more days we just got here