Ladder puzzle 2/Solution
From HexWiki
Red 9 makes the connection to the right solid. It also strengthens the connection to the red group below, which will be used for connecting to the top.
From here on, Red keeps playing on the e-file all the way to e3. If Blue intrudes at 12.g3 instead of 12.g2, Red must respond with 13.f4 but the remaining moves are similar.