I have two DSL connections. For the first I have an AVM Fritz Box for the second I use a D-Link router. I want to load balance all connections 50/50 from within my home network. I bought an OpenWRT Access Point with a managed switch for that.
From what I read, I would place each router in it's own subnet (i.e. fritz: 192.168.1.0/24 and d-link: 192.168.2.0/24), create a third subnet for my home network (i.e. 192.168.3.0/24), configure the switch of my OpenWrt box such that I have one port (at least) dedicated to each subnet, and finally I use mwan3 to load balance across the interfaces into the first two subnets.
My question though is: With this setup, would I be able to reach the Fritz Box (192.168.1.1) and the D-Link router (192.168.2.1) from within my home network, let's say some laptop (192.168.3.42)?
My guess would be that I could probably create a routing table on the OpenWrt box, but I'm (a) not sure, if that would really work and (b) concerned that it might interfere with whatever mwan3 is doing.
Another idea I had was to put everyone into the same network, i.e. OpenWrt box (192.168.0.1), Fritz Box (192.168.0.2), D-Link (192.168.0.3) and Laptop (192.168.0.42). That would actually be my preferred solution, but I'm not sure, how then to configure mwan3. When I create the wan interfaces in OpenWrt then I could use the static protocol, which would be assigned yet another IP inside 192.168.0.0/24. I've also seen, that I can select "unmanaged" as protocol for such a wan interface. However, how would mwan3 then know about the two router's IP addresses to route through?
The route will be already on the routing table as directly connected, as OpenWrt has an interface on all 3 networks. You should keep the default settings, that is applying NAT on the 2 wan interfaces, so nothing else needs to be done on the 2 ISP routers.
Unfortunately moving each router into it's own subnet didn't work. I think it should, but right now it fails to ping the routers from the vlan interfaces. Now my guess is that it failed because my device doesn't have a fully managed switch, i.e. it seems to be a 4+1 switch. I think I might have to configure each of the 4 ports of the switch identically in terms of networks (which I didn't in my previous attempt).
However, I read a bit more about mwan3 and how it's supposed to work. Earlier @trendy said, that it would not be possible to have home and the two routers in the same subnet. Why can I not create interfaces with dedicated static IPs inside the home network (including moving the routers into that same subnet) and then define both routers as gateway to either of these to interfaces. Why would mwan3 care, about the subnet of these interfaces?