Until now i used smb file transfer between a few android devices and a windows pc.
Herefore we need to make a small network with own wifi router.
But many times i have problems with change of ip adres, smb not installed, firewall etc.
Is there another way to transfer files where these problems don't exist?
Yes, Android does not have a firewall unlike Windows. So the first time a pop-up message appears with which you give permission for incoming FTP traffic for that IP address of your Android system. If you then change that specific address to ANY you can work with the same application from different Android devices including (basically with some ifs and buts) the Internet. I guess that's why it only works with the Internet because you probably worked with the same IP address every time.