WRT54G How Many simulaneous VPN tunnels

What this device supports (at least, in mine w/firmware v3.03.1) is not VPN endpoint support directly, but rather pass-through support of a couple of VPN protocols. So the device itself has no limitation; it's a matter of how many tunnels some system behind itself supports.

I do VPNs with openvpn these days, with an appropriate UDP port passed through to my server. The device is blissfully unaware of how many VPNs are running and just keeps chugging along.