How to open the desinated syncthing's instance?

I have installed two syncthing instance,both them are in running status.

sudo systemctl start syncthing@user1.service
sudo systemctl start syncthing@user2.service

How can i open syncthing’s gui for user1? Which user may open when i type 127.0.0.1:8384 in browser?

One will use 8384, one will use something else. The log output at startup and config.xml will contain the correct port to use.