[SOLVED] Websocket issue on AWS ec2

Hello everybody,

I followed the install guide for ubuntu 14.04 including the nginx ssl config.
Unfortunatly all users are offline and i have to reload the windows to see new messages so i guess websockets are not working. I saw the troubleshoting guide and rechecked the config but it still does not work.

I enabled the Debug Log and found the following messages.

[2016/09/12 09:34:39 UTC] [DEBG] /api/v3/teams/ppwqw14mwiysfdgkpqp1b3ghxh/channels/bwetokf4d7daxcofpxp68wo5cy/update_last_viewed_at
[2016/09/12 09:34:40 UTC] [DEBG] /api/v3/teams/ppwqw14mwiysfdgkpqp1b3ghxh/channels/
[2016/09/12 09:34:40 UTC] [DEBG] /api/v3/teams/ppwqw14mwiysfdgkpqp1b3ghxh/channels/k6397j51gir48qont41stcfgsh/extra_info
[2016/09/12 09:34:40 UTC] [DEBG] /api/v3/teams/ppwqw14mwiysfdgkpqp1b3ghxh/channels/k6397j51gir48qont41stcfgsh/update_last_viewed_at
[2016/09/12 09:34:40 UTC] [DEBG] /api/v3/teams/ppwqw14mwiysfdgkpqp1b3ghxh/channels/k6397j51gir48qont41stcfgsh/posts/page/0/60
[2016/09/12 09:34:40 UTC] [DEBG] /api/v3/users/profiles/ppwqw14mwiysfdgkpqp1b3ghxh
[2016/09/12 09:34:42 UTC] [DEBG] /api/v3/general/log_client
[2016/09/12 09:34:42 UTC] [DEBG] /api/v3/general/log_client:client code=0 rid=jpahyrc9pbf4xja5ja8qqqktao uid=d6zh1qeuwtbytkibepspotb44o ip=87.139.132.71 msg: Uncaught SyntaxError: Failed to construct ‘WebSocket’: The URL ‘undefined’ is invalid. row: 15 col: 24329 stack: SyntaxError: Failed to construct ‘WebSocket’: The URL ‘undefined’ is invalid. url: https://mattermost.domain.de/static/main.4441d5295935df20fce3.js [details: ]

Can anybody tell me what exactly the problem is?

Thanks.

edit: Domain URL anonymized.

SiteUrl Value was invalid but i could not figure out how to set it correctly.
Anyway… blank works fine.