So Jazz 4G in my house has quite low coverage. When I change the band to B8 only, the signals improve (from 1 to 3 bars) and the internet responsiveness is much better but the download speeds are slower. BUT, the VoLTE stops working.
The only issue is that on the newer Samsung firmwares, the band selection process has become quite a hassle instead of just dialing a code through Phone app.
EDIT: Found a way to make VoLTE work as well while having good coverage with B8. What I did was to enable 2G 900Mhz Band along with 3G 2100MHz and 4G B8.