I've recently changed my network to 192.168.2.1 (due to VPNing to my remote 192.168.1.0 location), however, there are several devices which have static IPs and are tricky to change (ESPHome).
Temporarily, can I disable my vpn interface to 192.168.1.0 and set up another LAN interface with 192.168.1.0 and bridge it to 192.168.2.0 so I can talk to the devices to change their config?
I've never done anything like this before, so may be using wrong terminology. Next step is to read up on bridging, however, I wanted to check that what I'm considering is even possible.
I guess the easiest thing to do would be setting a static IP address to your computer in the range of 192.168.0.0/24 (one that isn't otherwise occupied by one of your ESPHome devices) and just log into your ESPHome stuff and change their IP addresses.
This should work as long as all your network behaves as if it was a single wire (switches but no vlan and no routing otherwise involved) and as long your computer doesn't need internet connection while you change the ESPHome things.
Basically: If you have two device already connected to a single wire, you can give them both static IP addresses that are nowhere near the IP range of your router. Those devices will be able to communicate to each other, just not to the router. If all you need to do is access a web interface and adjust an IP address, that's enough.
I'd try that first. Just put a static IP address within the old IP range to your computer and adjust network settings. If that works you don't need to do anything to your OpenWRT router, hence no risk of breaking something. Not even disabling your VPN.
Another idea would be: Create another "interface" to your OpenWRT. Call it "intermediate". Give it a static IP address (192.168.0.1/24, I guess) and use "@lan" as device. This should "piggy back" a new interface on to the existing one. Disable DHCP for that "intermediate" device (as you don't want OpenWRT to send 192.168.0.x IP offers) and as well put "lan" as firewall zone to that new "intermediate" device.
See the first example, there's "lan" as primary network and "lan2" as an alias to "@lan", both have static IP addresses.
That's kind of a clumsy network setting. It's "kind of bridged" since it uses a single wire for two network segments. But it's routed since your 192.168.0.x devices will need to talk to 192.168.0.1 in order to jump over to 192.168.2.x and your 192.168.2.x devices will need to talk to 192.168.2.1 in order to jump over to 192.168.0.x.
And of course you need to turn off your VPN while doing so. That's why I'd start with the first option (adding a static IP address to your computer, not your router) first. You can keep your VPN setting fully intact.
Many thanks. I will give that a go. I hadn't considered that at all.
Can I just confirm, when you say 192.168.0.x, should that be 192.168.1.x? ie. the same network as my ESPHome devices? Sorry if I'm misunderstood.
Sure, my bad. You obviously got the point.