What you're asking is a way to set it so that when you are disconnects, it won't reconnect until you manually tell it to?
I think the easiest way to get it to behave like that:
- Set Connect Mode to "Keep Alive" (NOT "connect on demand")
- Set Check Interval to an arbitrarily high number. 86400 is the largest the gui will let you enter — that's 24 hours.
When you lose the connection, Tomato will wait the specified amount of time before trying to reconnect — regardless of what traffic is on your network. When you ACTUALLY want to reconnect, presumably sooner than that, go to the gui status page and hit the connect button (… or if it still shows as connected, or as reconnecting, hit disconnect then connect to reset it.)
But honestly, I agree with Ronnie: this connection sharing scheme sounds like a real headache.