The destination portal in the Nether in Factions has been blocked off and claimed by one faction. Anyone who comes through into the Nether is stuck; while in the portal effect, one can't use commands to TP out or /home, and logging out doesn't help; one simply winds up back in the portal upon returning.
Go to donations and get [Survival/ Factions] Stuck in a nether portal? Buy it, (It's free) Then you're back at spawn