Infuse webdav problem

Good afternoon, developers of INFUSE. When I use the webdav function of the INFUSE software, I can connect for a while, but I can’t connect for a while. I use the external network connection. I have a public network IP. There is no problem when using the internal network. I use the NPLAYER software. I tested the WEBDAV function of the external network, there is no problem at all, I hope to deal with it, thank you.