My phone and computer can both play the files fine, but using the official apps or webclient gives me an error. I'm assuming it's a transcoding error, but there shouldn't be one. The files (left untreated) work and even if they were transcoded, it should be fine. What am I missing here?

On a side note, how do I make files load 100% of the time?

Edit: I feel stupid, but I solved this. It turned out to be two separate issues. The unreliability was due to conflict in my Tailscale setup. Next, I reread the transcoding guide, and realized that I misread the HWA encoding and decoding charts when I was setting up my server; this was also a simple fix, just unchecking a single box.