Sadly, even with ppp module added seems no luck
On our server side FYI, the "instant drop" and "reconnect" shows as this if it's any help :
Sep 17 12:15:04 server vtund[32982]: Session vpn_raspberry_new[41.216.204.144:51900] opened
Sep 17 12:15:04 server vtund[32982]: LZO compression[level 9] initialized
Sep 17 12:15:04 server vtund[32982]: Blowfish-128-ECB encryption initialized
Sep 17 12:15:04 server vtund[32982]: Connection closed by other side
Sep 17 12:15:04 server vtund[32982]: Session vpn_raspberry_new closed
Sep 17 12:15:10 server vtund[33131]: Use SSL-aware challenge/response
Sep 17 12:15:10 server vtund[33131]: Session vpn_raspberry_new[41.216.204.144:51901] opened
Sep 17 12:15:10 server vtund[33131]: LZO compression[level 9] initialized
Sep 17 12:15:10 server vtund[33131]: Blowfish-128-ECB encryption initialized
Sep 17 12:15:11 server vtund[33131]: Connection closed by other side
Sep 17 12:15:11 server vtund[33131]: Session vpn_raspberry_new closed
Sep 17 12:15:17 server vtund[33243]: Use SSL-aware challenge/response
Sep 17 12:15:17 server vtund[33243]: Session vpn_raspberry_new[41.216.204.144:51902] opened
Sep 17 12:15:17 server vtund[33243]: LZO compression[level 9] initialized
Sep 17 12:15:17 server vtund[33243]: Blowfish-128-ECB encryption initialized
Sep 17 12:15:17 server vtund[33243]: Connection closed by other side
Sep 17 12:15:17 server vtund[33243]: Session vpn_raspberry_new closed
So that is why the compress or encryption I suspect is the issue - But hummm, not sure what I can do to poke more?
Perhaps it's interesting to note that the vtun process doesn't "die" - IOW, it stays the same PID so I do think vtun is "working" and it's maybe something related that can be solved?