Hi, I though I unswered to you in email.
I prepared the troubleshoot file, but got that the problem is not in the Antennas themselve. The issue appears once LTE signal is captured, than modem and the whole device is restarting. And again and again and again... The problem is with Tele 2 SIM card (i have two different). Tele2 is the only operator providing LTE in this location. So both SIM cards work just fine with laptop and couse the issue with RUT240. I've noticed that if Tele2 SIM card catch 3G (WDCMA) than it works fine, until it finds LTE signal...
P.S. I'have also checked the SMA - just fine.