After scratching my head for quite a few hours yesterday as to why larger file uploads werent working through the web interface (playing about the nginx and seafile confs), i finally found the right set of search keywords and discovered my issue was not seafile, but due to cloudflare having 100MB upload limits.
It would be a nice feature to have chunk upload type system to work around this limit. My web searching indicated some people had success using scripts like resumable.js. The users of a chunk system seem to indicate that it provides further reliability with large uploads via browser too.
It would be preferable to stay behind cloudflare for security, obscured ips, and ability to lock down access to the server, but i guess if this is not on the Seafile Radar/Roadmap there are alternate options we can take to further harden the servers and drop cloudflare.