I checked in those areas, and also the indoor site in Helsinki Airport, the B7 is not active.
Spoke with a contact in Telia, he said it is only on occasionally, for 3CA demo's, not for commercial use at this time.
this problem persists, even with newer flagship devices, like the Mi 8.
LTE 2CA and 3CA of B3 B7 B20 are not available which dramatically limits speeds in city areas… down to <5 MBit/s where, at the same location and time, my OP3 gets ~40 MBit/s
that is just sad…
Obviously the Mi 8 hogs on 800 MHz, which is always the strongest, but also the slowest/largest and most congested cell.