Peter, I also had problems to start the gateway. Which setting is wrong is hard to see. I got a tip from the Dragino help desk to reset the gateway. Then you have the possibility to start from scratch.
The reset button i located at the under side of the gateway. You have to take away the lock. See the attached picture.
Press the button for 30 seconds to reset the gateway.
There is a step-by-step installation guide for the Dragino DLOS8 gateway on our site as well, for future reference :-)
Worth checking the gateway EUI in the system log matches the gateway EUI in the LoRaWAN config page and on TTN. There was a discrepancy in mine. The system log had a slightly different EUI to the LoRaWAN config page and TTN server. I updated the EUI on the ttn server to match the system log and it all sprang into life.