How or who do you use for internet?

The reason I quit using WiFi and switched to SPRINT is: several times while parked at TA truck stops, I found that a truck going between me and the WiFi transmitter would boot me off even if I was parked in the FRONT ROW. I also discovered many times while I was connected to TA's WiFi; Flying J WiFi would boot me off.....even if Flying J was miles away.
Very aggravating.