5G21 Gateway loosing connection

5G21 Gateway has lost connection four times today. The power has not gone out. Usually I have to restart the gateway every 2 or 3 days because it gets real slow or looses connection. I read that these can overheat? I read some people have put an extra fan on it.  That should not have to be an option. Do I need a new gateway? My T-mobile phone connection has been fine.