No rule for this one
No ending or word group predicts the article of WLAN. Learn it as a pair and say it out loud: das WLAN.
das WLAN
It's das WLAN. WLAN is neuter.
Gibt es WLAN im Zimmer?
Is there Wi-Fi in the room?
No ending or word group predicts the article of WLAN. Learn it as a pair and say it out loud: das WLAN.