Not sure if you are still looking for feedback on the RC release (and if indeed this is the right way to do it).
I prototyped our network deployment (5 GHz backbone with 2.4GHz distribution & access), which involved 3.17.1RC1 on the following hardware:
- Rocket M5 XW
- Rocket M2
- PBE-M2-400
- NSM2
- NSM5 XW
- AirRouter
Your issue on port 4 is that it is used for DTD (Device-To-Device) connections to other AREDN nodes. You can attach your computers, etc to ports 1-3 for DHCP service. Use port 4 for connecting only to other AREDN flashed devices like a Nanostation, Rocket, Nanobridge on a tower or mast up in the air.