A portal lists nothing, or lists channels that will not start
Four portal failures that look the same on screen, and the one question that separates them.
Portals fail in a handful of specific ways, and mtivi reports what the portal actually said rather than a generic error.
The portal sent nothing back
The address answered, but with no data. Nine times out of ten the MAC is not registered on that portal, or the subscription behind it has ended. Send your service the MAC shown in the playlist form and ask them to confirm it is active.
The portal listed no channel categories
The session was accepted but your playlist carries no channels. That is a playlist problem at the service, not a setting in the app.
Channels are listed, but nothing plays
This is the classic shared MAC symptom. A portal will happily hand a channel list to a second device on the same MAC and then refuse every stream link. Give each device its own MAC, or ask your service to register a second one.
It worked yesterday and not today
Portals hand out sessions that expire, and they limit how often one MAC may reconnect. Open Settings, then Playlists, then Refresh Playlist to start a new session. If it fails again straight away, the playlist is more likely blocked or expired than broken.
Movies are there but series are missing
Each type is downloaded separately, and a portal can fail one while serving another. Refresh the playlist, and check the warning line the app shows after the sync: it names the part that failed.
Still stuck
Have this ready for your service: the portal address you entered, the MAC in the form, and the exact message the app showed. Those three answer almost every question they will ask.