Are you close to lava?
Nope it does freeze like after a few minutes
How can I speed it up?
Sleep / med.
How about when people are online?
Does the server happen to be expert? I believe — correct me if I’m wrong — that in expert mode the water must be a full block to freeze.
If not, you’ll probably just have to wait longer or place more torches.
It’s custom mode
If you zoom out does it have green squares like from the vine/tulip glitch? Try /repair?
The ice torches aren’t close enough to the water.