I gave this a try in the demo instance and I could upload a large file as well. @Mastadamus Can you check if you are able to reproduce this in our demo instance at https://my.demo.cloudron.io (username: cloudron password: cloudron). There's a bunch of large sample files that you can upload from this site - https://www.quinticsports.com/sample-videos/ . This will help us figure if this is related to browser or your network or your server etc.
Also, the error inside rocket.chat usually says the exact number like " File exceeds allowed size of 1 B. [error-file-too-large] ". Does it say 100MB in that error for you? That would mean the File Upload size setting did not get saved for some reason.
21537c50-4cb1-4911-94c4-f16aac44b35e-image.png