There might be an easier workaround for this:

Some hotspots only blocks new TCP connections when that time expires. So I used this workaround a few times in the past:

You open an SSH connection with -D 1337 so it creates a local SOCKS proxy. You need to keep that connection opened.

Then you go to gnome/kde/chrome/whatever and define a global SOCKS proxy to localhost:1337. By doing this, all your new TCP/UDP requests will go through that connection, and the router won't see them as new TCP/UDP connection.

It used to work for some airports and those 20-minutes-free wifi hotspots. But honestly I don't remember last time I had to use it. Nowadays I use mainly 3G on Brazilians airports and, when traveling abroad, I don't remember last time the airport didn't provide a unlimited free wifi.