Il243,
I do hope that you understand that you are asking two, maybe three different questions.
With Wifi, the first thing you should do is look at the signal strength, all system report this.
If you are someplace that you are trying to use the local Wifi and signal strength is more than half scale, but it is just slow, it may be bandwidth jammed. There is nothing you can do about that but take a nap and try again later when nobody is streaming YouTube.
If your access point is a good distance away (and you know it is there) but the signal strength is poor, then lots of things can help. Back when I had to do this I always used an Alfa device. An external 802.11(XX) and was able to work with access points that would otherwise be completely out of range. I still carry one when we travel, I have not fired it up in years.
If you are talking about cell phone boosters or repeaters (I won't go into the difference), yes, they work well if you mount a good outside antenna high on the coach. I have had several, those that were from Wilson Electronics (Weboost) were never a disappointment. They can require some attention to detail to install effectively. When traveling, we got some amazing places and were still connected.
While cell might look good a lot, never count on it for navigation because where you will need it most, it is most likely to fail.
Matt
Matt & Mary Colie
A sailor, his bride and their black dogs (one dear dog is waiting for us at the bridge) going to see some dry places that have Geocaches in a coach made the year we married.