Would you tell us the Plex Server version you’re using exactly, and the hardware it’s running on? Please also tell us about the player to which you’re trying to download, the hardware it’s on, and confirm that it’s located on your local LAN with the same subnet. Tell us about your LAN.
Restart your PMS computer and let it rest online for 6min to do internal housekeeping.
Then Screenshot the exact steps you are taking so people can reproduce this.
Zip and upload a sample image that doesn’t work for you so we can test the same thing.
Screenshot the exact error message you get.
Consider Settings - Troubleshooting - Download Logs so we can see this occur.
Thanks.