There may be instances where certain media sources in your library stop working. This can happen for any number of reasons that channel PEAR has little insight into as media is not hosted on our servers. You should take into account that the server hosting your media source may be experiencing an outage of some sort and may only temporarily be unavailable. It's recommended to not immediately delete sources from your library that aren't working, as some do come back online.
Due to the nature of IPTV, media sources posted in the media database should never be considered permanent. These are public streams that may stop or start working at any time. You should expect to keep updating your library with working sources often.
You can also check the media source status icon for more insight into the state of a specific source without having to add it to your library and test it first.