Technology has advanced to the point that modems on even cheap phones are pretty good. And in my personal experience, connectivity depends a lot on cellular band, as opposed to modem.
Here in Pakistan, we use Band 1, 3, 5 and 8 for LTE which have a frequency of 2100, 1800, 850 and 900 MHz respectively.
Higher frequency = better data speeds = lesser coverage. It's a trade-off.
Unfortunately, only Telenor and Jazz use low frequency 4G LTE (Band 8 and Band 5) so I'm sure you'll get much better LTE coverage in remote areas if you switch to either of these cellular carriers.
Band 1 and 3 are only really meant for densely packed urban areas as the signal can't travel far.