Off-topic, but: ABP should not cause “lot’s of problems”. The only problems ABP might give you, which OTAA does not:
- The need to reset frame counters when restarting a device. (Reset automatically for each OTAA Join Accept.)
- The need to program the network settings into the device. (Set automatically in an OTAA Join Accept.)
- Vendor lock-in to a specific network provider. (An OTAA node can join any network in its region, if you can make it perform a new OTAA Join when needed.)
So yes, OTAA is to be preferred (though it might be hard to join, if downlinks are not working), but once a node has succeeded an OTAA Join, it’s behaving exactly the same as an ABP node. On the other hand: if you’re doing an OTAA join very often, you might run out of nonces. So, for both ABP and OTAA, one should persist the node’s state if that’s not preserved when sleeping.