Connecting with Vodafone DSL router

[G.]

I am in Spain.  This apartment came with a Vodafone DSL router, an HG
556a.  It connects with a 3g dongle (HSDPA usb stick) which is
connected to the router- there are no cable or DSL connections.  To
connect, you load your browser and it takes you to a login screen.

Mostly it works.  Sometimes I have trouble connecting to the router
though.  Sometimes it is working fine and then quits.  Usually all I
have to do is reboot the browser.  Sometimes it seems to require that
I un-enable wireless in Network Connections (using Ubuntu 12.04) then
re-enable.

I am wondering if anyone has any suggestions for making the connection
more reliable and if possible skip the login step (not required in
Windows).

I am using a Samsung netbook.

Thanks

garyk