I do know Sonicwall fairly well…
You did add the portforwarding for the OpenVPN Port 1194, i assume, otherwise your VPN will not connect.
For your setup (I did have clients using similiar setups, just a different SoniccWall) using SonicWall, you basically need the following configured on your Network:
- All devices in your LAN use the SonicWall as default Gateway
- Your NethServer, as VPN Gateway, has only one real NIC, connected to your LAN.
- NethServer also uses SonicWall as default Gateway.
Specifically for your SonicWall:
- A port forwarding for OpenVPN Port 1194, pointing to the LAN-IP of your NethServer.
- An internal additional route for the OpenVPN network (10.99.12.0/24 as example), also pointing to the LAN-IP of your NethServer.
As I’ve migrated all my 30 clients from SonicWall to OPNsense, I presently don’t have access to a SonicWall to provide you with a screenshot of the SonicWall configuration…
I am aware of the fact that changing / adapting firewall rules in SonicWall is a real PITA, you often need to adapt in three different places, not just the list of rules.
Also, the wizard has major limitations creating several rules for one target, often enough, you end up with several entries of the same target server in the targets list.
Still, good luck!
My 2 cents
Andy