Some users feedback that they have to switch networks before sharing photos on Facebook, and they feel it is inconvenient. Actually, most high end mobile phones like iPhone and most of Samsung mobile phone do not need to switch WiFi to share photos directly through Ftp or Facebook. The reason is because these models support MultiPath TCP (MPTCP) protocol, and will automatically switch to another network available in case one does not work.
Setting as follows: (It may use mobile bandwidth. Generally, to share a single image size will not exceed 1M bytes)
Steps: