Hello. I have two devices: Huawei HG8245H5 ONT and Linksys WRT32X with OpenWrt 22.03.0 r19685-512e76967f.
Currently, my router is connected to the ONT with two cables: the first one goes from ONT's lan 1 port to router's wan port, and the second one goes from ONT's lan 2 port to router's lan 3 port. ONT is configured to bridge mode, and the router has an interface for wan port set to PPPoE. Second cable is used to access ONT's web UI on the same subnet as router's br-lan interface (192.168.1.0/24). ONT's static ip is set to 192.168.1.2.
I have already tried this tutorial, but it works by creating and interface with static address in another subnet.
My goal is to make my ONT's web UI accessible on 192.168.1.2 using single cable that goes to wan port on my router.
For this to be possible, your ONT must support the ability for you to specify VLANs on each of the ports... does it provide a user control over the network/VLAN and port assignments? Alternatively, you could feed the two connections into a managed switch and then a single cable between the switch and your OpenWrt router -- but that seems a bit silly, IMO, since it is adding a piece of equipment and certainly not simplifying your configuration.