Remember that if you just upgrade the wifi in the controller, then your controller will be able to reach Solo further out, but your Solo will not be able to reach your controller.
Its a two way conversation. So think of it this way, you can ask your solo to do something, but your solo wouldn't be able to reply back if it is out of range.
Its like using 2 way radio's. If you have a 10 watt 100 mile range radio, but your buddy only has a 1 watt 10 mile range, he can here you but you can't here him.