The custom trainers in Archlight provide experience, skills, and stamina to the character that is attacking them.
The teleport to get to the trainers is next to the monster teleport in the depot:
Stepping on trainers tiles gives you the options.
If you choose to stay connected you will gain stamina at a faster rate and can train your skills as normal and you need to keep your client on to not get kicked
you may instead pick a skill to train offline (Disconnecting your char) to gain skills offline, However, you will only gain stamina at a normal offline rate rather than quicker rate while connected
When you enter trainers make sure you see the orange message above your character.
If you enter trainers and instead of the orange message you see this, you need to get out for 60 seconds and then walk back.