Hi @janm Yes, RAK2245 in the Cellular Gateways uses i2c for the GPS data, and RAK2013 uses the UART. This is why you cannot use it this way. You can modify RAk2245 easily to change the route of the GPS to the i2c and to free up the UART path for RAK2013.
You need to remove R153 and R154 from RAK2245 concentrator HAT.
And yes, there is an error in the documentation due to different hardware variants in the past.
I sincerely apologies for this.
If you do not want to make this modification, please contact me at DM so we can arrange exchange.