When Cookiemonster mentioned it, I immediately started testing to move the local WAN out of the 192.168.1.0/24 subnet. Here's what I've done:
And now, it's working perfectly! Another lesson learned.
Initially, I thought that since it was separated from the main infrastructure (Docker + VM), it wouldn't be an issue. The fact that everything seemed to work fine as well confirmed my assumption that it was correctly set up, hehe. But after re-thinking to what you said, I now understand that OPNsense could get confused and NAT might not always function as expected. WAN traffic should indeed always come from a different subnet and require NAT. Otherwise, a packet might leave OPNsense via LAN but return via WAN, potentially causing issues.
See attached "Result.png" for the outcome!
Big thanks to you guys for your help, I truly appreciate it ;)
- Created a new VLAN with tag 178 on the switch
- Changed the modem's IP address from 192.168.1.254 to 192.168.178.254
- Kept the Synology NAS in the existing VLAN (192.168.1.0/24), but moved the modem from this VLAN to VLAN 178. Also, gave the Synology NAS access to VLAN 178 so that I could relocate the local WAN IP to the new 192.168.178.0/24 subnet.
- Changed the local WAN IP in OPNsense from 192.168.1.2 to 192.168.178.1, with the gateway set to the modem (192.168.178.254)
And now, it's working perfectly! Another lesson learned.
Initially, I thought that since it was separated from the main infrastructure (Docker + VM), it wouldn't be an issue. The fact that everything seemed to work fine as well confirmed my assumption that it was correctly set up, hehe. But after re-thinking to what you said, I now understand that OPNsense could get confused and NAT might not always function as expected. WAN traffic should indeed always come from a different subnet and require NAT. Otherwise, a packet might leave OPNsense via LAN but return via WAN, potentially causing issues.
See attached "Result.png" for the outcome!
Big thanks to you guys for your help, I truly appreciate it ;)