Which public wifi?
It's just a web page so how come it won't work via a VPN?
VPN routes requests to your own network. Login page is local to the AP, not routable from your network.
AP refuses to route traffic for clients who haven't got a login token, hence you have no VPN connection anyway.
Maybe I'm using the wrong phrase, by VPN, I mean a VPN tunnel. could be SSH, but you'd still have the situation described, so would need an exemption for the tunnel for public-wifi-requiring-login.
VPN routes requests to your own network. Login page is local to the AP, not routable from your network.
AP refuses to route traffic for clients who haven't got a login token, hence you have no VPN connection anyway.
Maybe I'm using the wrong phrase, by VPN, I mean a VPN tunnel. could be SSH, but you'd still have the situation described, so would need an exemption for the tunnel for public-wifi-requiring-login.