On Android (and I think iOS, too) you can restrict WIFIs, when they are behind a data plan access, e.g. a 3G/4G internet access. I have this everyday, when travelling by train in Germany. The WIFI access itselve is for free, but limited in bandwith and data usage per guest. Everytime I connect to the WIFI, Spotify starts updating the playlists and downloading the songs.
As I have marked the WIFI on the train as restricted, my Android and as it seems all other apps respect this and just use this WIFI for "normal" internet access, but no mass downloads or system updates. Unforntunately Spotify doesn't respect this.
Great, @E-J-D.
We're glad to hear it worked that way.
In this case, we suggest you keep the Offline Mode on when traveling to avoid using the WiFi connection.
For this reason, we're setting this post as "Closed". If you keep getting the same issue with this feature on, don't hesitate to create a new thread.
Enjoy the music!