Hi.
We had the same need and Peplink developped a firmware including NULL Encryption in phase 2. We tested it and it was successfull. I think this should be included in next firmware version.
Note : I didn’t manage to make it work with UNC, that’s a question to Peplink
Note 2 : the Lifetimes we use are not standard (specific firmware developped by Kenny) but you can put standard Lifetimes there for your tests.