Ignoring sync interfaces settings

[Myppomeu]

Steps to reproduce

1. Install Nextcloud SMS
2. Set only Wi-Fi sync
3. Turn Wi-fi off

Expected behaviour

Expected that app would sync only over Wi-Fi.

Actual behaviour

Nextcloud SMS ignores settings, try to sync over 4G, cannot find server (my server is local only) and displays error about it.

Server configuration

Nextcloud version: 12.0.3

PHP version: 5.6.30+dfsg-0+deb8u1

Webserver: nginx 1.6.2-5+deb8u5

HTTPS: no

Client configuration

Android version: 7.1.2 (LineageOS 14.1)

Phone: Xiaomi Redmi Note 3 Pro (replicates on every phone I test)

Nextcloud SMS app version: 1.3.1 (error appears in previous versions too)