FTPServer hanging on two phones, but really stable on another

[Craig Fryer]

Very strange problem that appears to have been occurring on two handsets, but not a tablet.

FTPServer V2.9.1 (66) can be stable for several days on these two handsets (only one is still operational). During this time I can transfer from the handset and delete 10,000s of small JPG files using Filezilla. Then for an as yet unknown reason the FTPServer will become unresponsive. Sometimes simply unlocking the handset and task switching to and from the app is enough to restart the connection to FTPServer. Sometimes it requires a reboot. Then one time I had to clear all the settings using the application manager and re-enter them.

Currently the handset that is having problems is a Samsung S3 LTE (GT-i9305) model (2GB RAM) running Samsung's standard Android 4.4.4.

The other handset that was having the same problem was an Alcatel pixi 3 (4.5)  running Android Lollipop 5.1 with 1GB of RAM and a MT6735M. (Not working at the moment)

All three handsets I have been using in this particular usage case are running IP Camera Viewer Pro in record mode. They not are used to do anything else. The handset/tablet that isn't having this problem is recording a different set of cameras.

I doubt the problem is specifically with FTPServer, just that it is being tripped up.