Results of getting disconnected while attacking a village

When I go 'trophy farming' (attacking those village with Town Hall unguarded), I deploy around 3-5 archers to destroy the Town Hall.

After some time I get disconnected while I'm still attacking.

However, when I reconnect and see my Attack Log, it says that I got 1 star although I lost connection.

Do all attacks like this that get disconnected results in 1 star? Or does it follow any rule?

When you disconnect the attack keeps going on the server with the troops you deployed.

In your case, they are able to destroy the townhall which results in one star. After that, the attack keeps going on the server. When the attack ends, because the time ran out or all troops have been killed you are awarded with the loot, the league bonus (if you got at least one star) and the trophies.