I finally got it to work propery via GUI only and without tunables. I have 2 physical interfaces, igb0 and igb1 and two jails that i want to have on a separate interface each. So jail 1 connects to igb0 and jail 2 connects to igb1.
For jail 1, settings in GUI:
- In the basic properties screen, select VNET and choose VNET0 as the ipv4 interface and fill in the IP, subnet and gateway (of course in the network you are connecting to).
- In the network properties, under interfaces, type: VNET0:bridge0 (if it's not already there)
- Also in the network properties, set the vnet default interface to igb0
For jail 2, settings in GUI:
- In the basic properties screen, select VNET and choose VNET0 as the ipv4 interface and fill in the IP, subnet and gateway (of course in the network you are connecting to).
- In the network properties, under interfaces, type: VNET0:bridge1
- Also in the network properties, set the vnet default interface to igb1
- Also in the network properties, under resolver, type: nameserver <your dns IP>;nameserver <your dns IP> (and other options you want in the resolv.conf file of the jail). You can leave it empty/default if you vant to use the same as the host's file (The Freenas file itself) <--I did not need this for jail 1, since that one is on the same network as the nas itself, so it uses the same dns settings, but it i did need that for jail 2, since there i use a different dns server.
So for me the 2nd and 3rd bullet were (mainly) the culprit and with these settings everything is working perfectly :)
EDIT: forgot the 3rd bullet