IOS App problem with WebSocket port (appears with v3.3.0 and 3.4.0)

With IOS app i got this message all the time since 3.3.0 and 3.4.0:
" Please check connection, Mattermost unreachable. If issue persists, ask adminsitrator to check WebSocket port."

From 3.2.0 to 3.3.0
didn't change anything in config.json or nginx.conf (in conf.d):

server {
listen 80;
server_name sllmatter.se;
return 301 https://$server_name$request_uri;
}

server {
listen 443 ssl;
server_name sllmatter.sll.se;

ssl on;
ssl_certificate /etc/nginx/conf.d/sllmatter.pem;
ssl_certificate_key /etc/nginx/conf.d/sllmatter.key;
ssl_session_timeout 5m;
ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
ssl_ciphers 'EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH';
ssl_prefer_server_ciphers on;
ssl_session_cache shared:SSL:10m;

location / {
gzip off;
proxy_set_header X-Forwarded-Ssl on;
client_max_body_size 50M;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
proxy_set_header Host $http_host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Frame-Options SAMEORIGIN;
proxy_pass http://127.0.0.1:8065;
}
}