LoRaWAN devices have 2 ways of joining the network, OTAA or ABP.
In general, unless you have specific requirements, OTAA is easiest, well supported, and recommended by Digital Matter.
Some issues have been discovered with ABP on LoRaWAN 1.1.
DM view 1.1 as currently 'experimental'. There are some known issues and the spec is not regularly updated by the Alliance.
Please see below for known errors. 1.0.3 will need to be used if set up with any of these networks.
Chirpstack incorrectly calculates the MIC for confirmed downlinks
This is reportedly fixed in 3.14, but DM have not yet tested.
TTN doesn’t implement the FOpts encryption errata for LoRaWAN 1.1