I have managed to send data to TTN and see it appear in the TTN API.
For now my hardware test looks fine. For some reason I could not perform a OTA join and also the ACK's are not working.
I tested it at a GW location nearby, but perhaps I need to test it again at the GW you mentioned. Hopefully next wek our own GW is up-n-running, making more thourough testing easier.