Looks like something is crashing the eventserver. I've added the some logging below.
In the tokens.txt file, there is only one token. No sign of a duplicate token. Can I safely remove the tokens.txt file?
May 23 15:07:21 ubuntu zmeventnotification[6418]: INF [got a websocket connection from 62.235.12.42 (1) active connections]
May 23 15:07:21 ubuntu zmeventnotification[6418]: INF [Websocket remotely disconnected from 62.235.12.42]
May 23 15:07:21 ubuntu zmeventnotification[6418]: INF [got a websocket connection from 62.235.12.42 (1) active connections]
May 23 15:07:21 ubuntu zmeventnotification[6418]: INF [Websockets: New Connection Handshake requested from 62.235.12.42:58030 state=pending auth]
May 23 15:07:21 ubuntu zmeventnotification[6418]: INF [Correct authentication provided by 62.235.12.42]
May 23 15:07:21 ubuntu zmeventnotification[6418]: INF [Duplicate token found, removing old data point]
May 23 15:07:21 ubuntu zmeventnotification[6418]: INF [Storing token ...14LdUdzLec,monlist:1,2,intlist:0,0,pushstate:enabled]
May 23 15:07:21 ubuntu zmeventnotification[6418]: INF [SaveTokens called with:monlist=1,2, intlist=0,0, platform=android, push=enabled]
May 23 15:07:21 ubuntu zmeventnotification[6418]: FAT [Cannot open for write /etc/private/tokens.txt]
May 23 15:07:21 ubuntu zmdc[6365]: ERR ['zmeventnotification.pl' exited abnormally, exit status 255]
May 23 15:07:21 ubuntu zmdc[6365]: INF [Starting pending process, zmeventnotification.pl]
May 23 15:07:21 ubuntu zmdc[6365]: INF ['zmeventnotification.pl' starting at 17/05/23 15:07:21, pid = 6501]
May 23 15:07:21 ubuntu zmdc[6501]: INF ['zmeventnotification.pl' started at 17/05/23 15:07:21]
May 23 15:07:22 ubuntu zmeventnotification[6501]: INF [Push enabled via PushProxy]
May 23 15:07:22 ubuntu zmeventnotification[6501]: INF [direct APNS disabled]
May 23 15:07:22 ubuntu zmeventnotification[6501]: INF [Event Notification daemon v 0.93 starting]
May 23 15:07:22 ubuntu zmeventnotification[6501]: INF [Total event client connections: 1]
May 23 15:07:22 ubuntu zmeventnotification[6501]: INF [Reloading Monitors...]
May 23 15:07:22 ubuntu zmeventnotification[6501]: INF [Loading monitors]
May 23 15:07:22 ubuntu zmeventnotification[6501]: INF [Checking
https://185.124.74.36:8801 reachability...]
May 23 15:07:23 ubuntu zmeventnotification[6501]: INF [PushProxy
https://185.124.74.36:8801 is reachable.]
May 23 15:07:23 ubuntu zmeventnotification[6501]: INF [About to start listening to socket]
May 23 15:07:23 ubuntu zmeventnotification[6501]: INF [Secure WS(WSS) is enabled...]
May 23 15:07:23 ubuntu zmeventnotification[6501]: INF [Web Socket Event Server listening on port 9000]