Answer this before you touch a setting, because the three cases have different owners. One channel dead while its neighbors play is a single source feed, and nothing on your Fire TV Stick will revive it. A whole category dark, every feed in one group, is almost always server-side, since a local fault has no way to pick out one group and leave the rest running. Nothing at all playing, with the channel list still drawn on screen, points at the line, the login session, or the device itself. Write down which of the three you have. Every step below assumes you know it, and support teams close tickets faster when the first line reads as a scope rather than as it stopped working.

1. 1One channel: source feed, not your setup
2. 2One group: server-side, report it with the group name
3. 3Everything: line, session, or device memory

Audio without video means the stream arrived and the audio track decoded fine, so the network is not your problem. The video track is what the chip refused. Fire TV hardware decoders are fussy about certain HEVC profiles and about frame-rate switches during the handshake. Two changes cover most cases: set the player engine or decoder from hardware to software inside the app, and on the stick set Display and Sounds to a fixed 1080p output with Match Original Frame Rate turned off. Software decoding costs CPU, so if a 4K feed then stutters, keep hardware decoding and watch the 1080p version of the same channel. Testing the same stream in VLC tells you in seconds whether the fault sits in the codec or in the app.

Three things move while you sleep. Fire OS installs system updates on its own schedule, and a sideloaded player built against the previous release can regress the morning after. The app itself may auto-update, and post-update regressions in player builds are a recurring cause rather than a rare one, which is why keeping the previous APK on a USB drive is worth the two minutes. Third, the app cache grows and eventually holds stale portal responses, so the app connects to nothing and reports a connection error. Clearing cache is the cheap test here, not a ritual: if clearing it restores service, the stale-data path was the cause and you can stop looking at your router.

1. 1Fire OS updated: reinstall the current player build
2. 2App updated: try the prior build before blaming the line
3. 3Cache cleared and it works: stale portal data was the fault

A Fire TV Stick carries roughly 1.5-2 GB of RAM and gives your player far less than that once the launcher and background apps take their share. Player apps hold the entire visible channel list in memory, and they destabilize somewhere around 18,000 visible channels, which is why hiding groups you never open is a real fix and not housekeeping advice. On a catalog the size of ours, 54,000-plus live channels, showing everything is the fastest way to make a small device unstable. Hide all but the groups you watch, then hold Select and Play or Pause together for about five seconds for a full restart that actually clears RAM. A power-cord pull does the same job; the remote power button does not.