The other thing is with poor signal you might look into using something like a Mikrotik SXT LTE6 Kit or even a LHG LTE6 kit if necessary. I note that these are brand new version of previous products with a CAT6 LTE modem, which is an improvement over the older ones which are only CAT4 from memory. Though they still come with a 100Mbps ethernet port which does limit things somewhat. However I guess a working 4G connection limited to 100Mbps is going to be a massive upgrade.

They are designed to be mounted outside pointed directly at the mobile phone mast. Best powered using PoE with some Cat5e or better. You can use them as your router directly with a cheap PoE switch or put them in pass through with something like a Ubiquiti Edgerouter X SFP or Mikrotik hEX PoE. For WiFi user some separate WiFi access points say cAP Lite/cAP from Mikrotik or the UniFi AC-Lite/AC-LR from Ubiquiti.

I will second Mikrotik SXT/LHG external mounted kit. You just set them up once and they work without issues.

The problem with the Mikrotik SXT LTE6 Kit is that it doesn't support carrier aggregation across band 1 and 3 so won't give the highest speeds in many Three areas - which is a shame as it's a nice bit of kit.