Thanks all for the replies 🙂
Support asked if the E3372 supports LTE 1800 which of course it does. It doesn't support frequency locking though and that's something that DNA also referred to when I had speed problems on their network a while back as well.
I bought a MiMo antenna and have it placed on a window etc and it seems to help a little, no miracles though as the E3372 does well on the DNA network right now. That can change though of course 😉
E3372 Telia 4G
Ping 14, 21/4 http://www.speedtest.net/result/6988488360
Ping 16, 24/3.7 http://www.speedtest.net/result/6988492892
E3372 + MiMo Telia 4G
Ping 16, 34/7 http://www.speedtest.net/result/6988503313
Ping 18, 31/5 http://www.speedtest.net/result/6988505401
Ping 17, 24/4 http://www.speedtest.net/result/6988508066 (MiMo not helping, if it helps at all)
I'll call support today and keep testing.
[EDIT] Support said a new base station will be added in the area end of March so maybe things will improve.