[Solved] Android App not connecting outside

[TheDreadPirate]

If my syno use IPV6 .... applications dont work, browsers ok
if my syno doesn't use IP V6, applications work. browsers ok

Could you please specify, what you mean by "Syno uses IPV6" and "Syno doesn't use IPV6"? I'm having the exact same symptoms as you described.

Some router's don't implement IPv6 very well.  Or don't implement it in a way that would allow the clients to be remotely accessible.

The OP was probably in that situation and they disabled IPv6 on their Synology NAS so that they were IPv4 only.  The server would no longer attempt to make IPv6 connections.