Using Virgin Media Hub 5x for WiFi AP and modem, but OpenWRT for routing

Why? Virgin Media Hub 5 and 5x are excellent WiFi APs, especially for shit positions. Custom isn't always better, and it's fun to see people realise this when they ask why their fancy OpenWRT + standalone AP setup is slower than just using their ISP router.

However the Virgin Hub is a dog tier router missing many essential features, so I went looking for the best of both worlds - keeping it as an AP, and not spunking £100 (and extra power) on a WAS-110 to replace it as a modem.

General consensus is this is impossible (or at least a bad idea), and AI hallucinated a bullshit approach that would never work. All it took was 2 ethernet cables...

• Disable DHCP on Virgin Hub
• Connect 10G port on Hub 5x to OpenWRT WAN (directly)
• Connect any other port on Hub 5x to LAN switch. This becomes the route for WiFi traffic, so 1G bottleneck, but not a big deal at all
• Static IP 192.168.0.2 or similar on OpenWRT WAN port
• OpenWRT LAN on 192.168.69.1/24 subnet
• DHCP options 3,192.168.69.1 and 6,192.168.69.1 on OpenWRT LAN port, so that WiFi devices connecting to the Hub 5x end up on the right subnet and route all their internet traffic through OpenWRT
• Personally I kept DMZ off on Hub 5x as I don't need port forwarding

Overall seems reasonably secure - even if the Hub 5x was compromised, it is difficult/impossible to change its subnet, so it can't easily communicate with the rest of the LAN directly. Also you can put a Pi on the Hub 5x's subnet as an emergency backdoor in case of OpenWRT failure etc.