Clients verbinden sich nicht

habe seit heute Mittag das Problem, dass sich die Clients (Windows und Android) nicht mehr mit dem Server verbinden:
Die Verbindung zu Nextcloud auf xxx Operation abgebrochen

Über das Web kann mich ganz normal einloggen, Ordner erstellen und Daten hochladen.

Habe zum testen noch mal eine 2te nextcloud installiert. Dort funktioniert alles ganz normal. Woran kann das liegen??
Benutze die aktuelle Version von nextcloud.
Log:

{“reqId”:“IfXRNbPzKS+QlQmxY9H0”,“remoteAddr”:“ip”,“app”:“PHP”,“message”:“Unknown: send of 5 bytes failed with errno=32 Broken pipe at Unknown#0”,“level”:3,“time”:“2016-09-04T16:36:08+02:00”,“method”:“GET”,“url”:"/cloud/ocs/v2.php/apps/notifications/api/v1/notifications?format=json",“user”:“XXXXX”}
{“reqId”:“CEQxIiJy3laLHzh3OxKK”,“remoteAddr”:“ip”,“app”:“PHP”,“message”:“Error while sending QUERY packet. PID=2941 at /var/www/cloud/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOStatement.php#91”,“level”:3,“time”:“2016-09-04T17:48:51+02:00”,“method”:“PROPFIND”,“url”:"/cloud/remote.php/webdav/",“user”:"–"}
{“reqId”:“CEQxIiJy3laLHzh3OxKK”,“remoteAddr”:“ip”,“app”:“webdav”,“message”:“Exception: {“Message”:“HTTP\/1.1 503 Doctrine\\DBAL\\Exception\\DriverException: An exception occurred while executing ‘SELECT id, uid, login_name, password, name, type, token, last_activity, last_check FROM oc_authtoken WHERE token = ?’ with params [\“40174bc2c363459800da35c34ca681b0b3719be8c6bfe310db70e707bd184ebe13bfd7e744f52aadc1fb3030fa5909af4785651858e8aa3e24cded9fedf300eb\”]:\n\nSQLSTATE[HY000]: General error: 2006 MySQL server has gone away”,“Exception”:“Sabre\\DAV\\Exception\\ServiceUnavailable”,“Code”:0,“Trace”:”#0 \/var\/www\/cloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Auth\/Plugin.php(163): OCA\\DAV\\Connector\\Sabre\\Auth->check(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#1 [internal function]: Sabre\\DAV\\Auth\\Plugin->beforeMethod(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#2 \/var\/www\/cloud\/3rdparty\/sabre\/event\/lib\/EventEmitterTrait.php(105): call_user_func_array(Array, Array)\n#3 \/var\/www\/cloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php(446): Sabre\\Event\\EventEmitter->emit(‘beforeMethod’, Array)\n#4 \/var\/www\/cloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php(248): Sabre\\DAV\\Server->invokeMethod(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#5 \/var\/www\/cloud\/apps\/dav\/appinfo\/v1\/webdav.php(60): Sabre\\DAV\\Server->exec()\n#6 \/var\/www\/cloud\/remote.php(165): require_once(’\/var\/www\/cloud\/…’)\n#7 {main}",“File”:"\/var\/www\/cloud\/apps\/dav\/lib\/Connector\/Sabre\/Auth.php",“Line”:162,“User”:false}",“level”:4,“time”:“2016-09-04T17:48:51+02:00”,“method”:“PROPFIND”,“url”:"/cloud/remote.php/webdav/",“user”:"–"}
{“reqId”:“ucuj8Knm3aHZ2F3brRK/”,“remoteAddr”:“ip”,“app”:“core”,“message”:“Login failed: ‘xxxx’ (Remote IP: ‘ip’)”,“level”:2,“time”:“2016-09-04T21:02:51+02:00”,“method”:“POST”,“url”:"/cloud/index.php/login",“user”:"–"}
{“reqId”:“8zGUaBP9YuIbC0+x53Hb”,“remoteAddr”:“ip”,“app”:“PHP”,“message”:“Error while sending QUERY packet. PID=3568 at /var/www/cloud/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOStatement.php#91”,“level”:3,“time”:“2016-09-04T21:08:53+02:00”,“method”:“PROPFIND”,“url”:"/cloud/remote.php/webdav/",“user”:"–"}
{“reqId”:“8zGUaBP9YuIbC0+x53Hb”,“remoteAddr”:“ip”,“app”:“webdav”,“message”:“Exception: {“Message”:“HTTP\/1.1 503 Doctrine\\DBAL\\Exception\\DriverException: An exception occurred while executing ‘SELECT id, uid, login_name, password, name, type, token, last_activity, last_check FROM oc_authtoken WHERE token = ?’ with params [\“40174bc2c363459800da35c34ca681b0b3719be8c6bfe310db70e707bd184ebe13bfd7e744f52aadc1fb3030fa5909af4785651858e8aa3e24cded9fedf300eb\”]:\n\nSQLSTATE[HY000]: General error: 2006 MySQL server has gone away”,“Exception”:“Sabre\\DAV\\Exception\\ServiceUnavailable”,“Code”:0,“Trace”:”#0 \/var\/www\/cloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Auth\/Plugin.php(163): OCA\\DAV\\Connector\\Sabre\\Auth->check(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#1 [internal function]: Sabre\\DAV\\Auth\\Plugin->beforeMethod(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#2 \/var\/www\/cloud\/3rdparty\/sabre\/event\/lib\/EventEmitterTrait.php(105): call_user_func_array(Array, Array)\n#3 \/var\/www\/cloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php(446): Sabre\\Event\\EventEmitter->emit(‘beforeMethod’, Array)\n#4 \/var\/www\/cloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php(248): Sabre\\DAV\\Server->invokeMethod(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#5 \/var\/www\/cloud\/apps\/dav\/appinfo\/v1\/webdav.php(60): Sabre\\DAV\\Server->exec()\n#6 \/var\/www\/cloud\/remote.php(165): require_once(’\/var\/www\/cloud\/…’)\n#7 {main}",“File”:"\/var\/www\/cloud\/apps\/dav\/lib\/Connector\/Sabre\/Auth.php",“Line”:162,“User”:false}",“level”:4,“time”:“2016-09-04T21:08:53+02:00”,“method”:“PROPFIND”,“url”:"/cloud/remote.php/webdav/",“user”:"–"}

Ich habe exakt das gleiche Problem.
WindowsClients wie Linuxclients

Bei mir das gleiche Problem. Habe die gleiche 13er nextcloud auf 2 Servern laufen. Bei dem einen gibt es Verbindungsprobleme, bei dem anderen nicht. Auch nicht immer. Hat jemand bereits eine Lösung?