I guess you are using iOS for Apple Devices, because you didn't say what OS you are using and what for Device
Have a look here how to ask for help
viewtopic.php?f=2&t=5506I have deleted iSub for a while because it has some serious bugs because there was no update for more than two years. The last fixes are for iOS 8 and 9, we are at 13 and 14 is coming (imho) soon.
Substreamer is free, but has also bugs, sometimes crashing, playing MP3 well and direct, ALAC lossless don't start playing you have first to press Pause and than play again.
https://apps.apple.com/de/app/substreamer/id1012991665I suggest play:SUB. Michael is very friendly if you need help, very active removing bugs and adding new features to the app.
Of course it's not for free but 5,49.-€ is a good deal. I'm running also Airsonic and it works for both Server very good, a few small cosmetic bugs for now, but over all the best
https://apps.apple.com/de/app/play-sub- ... d955329386AVsub is also a good iOS App, but it has very Basic Music Functions (my opinion), creating and adding Tracks to playlists is a bit tricky. As far as i can see, it is limited to two servers Michaels not, actual I have my two servers and two from friends.
It seems to me that AVsub is more for Videos BUT if you have a video organized that is good for Kodi, it is not good for AVsub. The settings with long scrolling titles are not easy to unnderstand (for me)
Only music is 4,49.-€ but for every feature you have to pay again, if you need it only.
https://apps.apple.com/de/app/avsub/id923424694 Remember, even if you have to buy both apps, if you don't like it, you can give it back and you get your money from Apple Store. It's a bit tricky but have a look at the web for further inormation.
I have more than 260.000 Titles round about 50% ALAC lossless and using both Apps at a 512GB XS Max.
I'm using also Android and have to say both App are miles away from the Android Apps (available in Germany)