Bad Connectivity

so I have been banging my head against the wall because I cannot fix my problem. Maybe someone on here knows something. In short: I have a really bad SNR with this library that doesn’t really allow me to do any measurements outside.

I am using a Nucleo L152RE and a SX1276MB1MAS Shield. Furthermore I use the Arduino Platform with the ttn-otaa.ino example from the github page. I disabled ADR and even played around with the setTxPow command but something seems to help. When the gateway and the node are in the same room I get an SNR of like 8 but also dropping down to 2 or even 0 sometimes. Going into a different room immediately results in full packet loss. I tried different antenna’s but nothing seems to help.

Now using a different node (Adafruit Feather M0 LoRa) and the RIOT OS Library with the same antenna I get way better SNR values. Constantly between 12-14 when in the same or even different rooms.

Does anyone have an idea where this bad connection could come from?