So I've had problems reaching my homelab stuff remotely because of the annoying businesses that don't have modern ip address support. I had already solved this for my laptop with a small script that just enables a wireguard vpn to enable a ::/0 route when it doesn't detect a valid v6 on the current network, but I've never had something like this for my phone. Luckily, the phone already has a connection that's more reliable than a personal vpn and almost always supports modern addresses: the cellular modem. I've just never seen an app that takes advantage of this for legacy-only networks. This is why I decided to set one up myself. Admittedly, this is vibecoded, but I've been testing it for a few days on legacy only and normal networks, and it seems to work well. The way this functions currently is that it detects whether your current WIFI connection has IPv6 routes and then if yes, turn off the "vpn" or if no, turn on a "vpn". In this case, the "vpn" is really just a local proxy that routes v6 through your cellular and leaves v4 going through the WIFI like normal. Because of the way it's currently done, pings don't work (it goes through a SOCKS5 local proxy) but tcp and udp both work fine. Currently only supported on android 17+. https://gitlab.com/unixeno/supplement-ipv4-only-wifi-with-cellular-ipv6/