I would have a look at the Cellmapper web site which tells you all you need to know about the cell sites with a map display, the cell ID's and the bands in use.
The information relies on crowd sourced data from users using a phone app. Sometimes by selecting particular bands or even 1 band only you will see an improvement in service or can force the router to use another mast, this is assuming your router allows that, not all do. I have read that an update on one router (Three) recently had that option removed by an update.
Getting the best from your particular situation can be trial and error
