Every Dokany mounted Vault has a timeout variable, giving a treshold in milliseconds. Everytime a call (for example “read file X”) to the virtual filesystem is made, a timer starts. It stops either if the call is handled (the file is actually read), or it hits the threshold, where the drive is unmounted forcefully. It’s a security measure of Dokany to not crash your machine when it starts choking on such calls.
As you already pointed out, the counter measures are to change the custom mount flags to
- increase the time out and/or
- increase the number of threads (these handle file system calls).
If there are a lot of calls to the file system, this may happen since even Dokany is faster than WebDAV, decryption takes its time. For example if you have 4 worker threads, and list currently 4 big directories, other calls cannot be handled and may cause a forceful unmount.