Ok, you’re a console guy. Totally fair, can configure a few bit more options, in specific way.
I’ve used only GUI to configure NethServer to Zyxel USG device with some… tricks.
Therefore…
A couple of hints:
- NethServer should be the initiator of the tunnel and USG should be configured as standby (currently Nethserver do not allow it)
- keep tracking of the timeouts and time, date and timezone of both devices
- double check compression (consider to disable it) and DPD (consider to enable it on both sides)
- unfortunately into GUI there’s no specific configuration for IKEv1 or v2
- unfortunately act II, no certificate support
Last hint: does Ubiquiti USG support OpenVPN too? This could be another option too…