I tried the file manager, but it is not working correctly, it’s not loading all the files, reverts back to the base directory and takes over 3 minutes to open a file – I guess the firewall does not like that either. If it’s possible to adjust the firewall, I strongly suggest that.
Either way, I will try to replicate this on one of our test servers with the highest firewall settings to see if I can get the same errror and go from there. This is unfortunately not a simple plug fix, first I need to be able to tell what exactly triggers it.
I will get back to you soon.