Redis connection refused

[Heinz E. Silkeit]

Hi ....
from one to another day my redis installation in Nextcloud didn't work anymore. I get every 15mins 

Info	cli	Memcache \OC\Memcache\Redis not available for distributed cache	2018-04-07T13:00:01+0200
Info	cli	Memcache \OC\Memcache\Redis not available for local cache	2018-04-07T13:00:01+0200

I have checked the config.php  as described in Nextcloud manual, can't find any errors

'memcache.local' => '\\OC\\Memcache\\Redis',

  'filelocking.enabled' => true,

  'memcache.distributed' => '\\OC\\Memcache\\Redis',

  'memcache.locking' => '\\OC\\Memcache\\Redis',

  'redis' => array (

    'host' => '/var/run/redis/redis.sock',

    'port' => 0,

    'timeout' => 0,

    'dbindex' => 0,

    'password' => 'XXXXXXXXXXXXXXXXj', 


The Server Log

1168:M 07 Apr 13:13:01.382 # You requested maxclients of 10000 requiring at least 10032 max file descriptors.

1168:M 07 Apr 13:13:01.386 # Redis can't set maximum open files to 10032 because of OS error: Operation not permitted.

1168:M 07 Apr 13:13:01.386 # Current maximum open files is 4096. maxclients has been reduced to 4064 to compensate for low ulimit. If you need higher maxclients increase 'ulimit -n'.

                _._                                                  

           _.-``__ ''-._                                             

      _.-``    `.  `_.  ''-._           Redis 3.0.6 (00000000/0) 64 bit

  .-`` .-```.  ```\/    _.,_ ''-._                                   

 (    '      ,       .-`  | `,    )     Running in standalone mode

 |`-._`-...-` __...-.``-._|'` _.-'|     Port: 0

 |    `-._   `._    /     _.-'    |     PID: 1168

  `-._    `-._  `-./  _.-'    _.-'                                   

 |`-._`-._    `-.__.-'    _.-'_.-'|                                  

 |    `-._`-._        _.-'_.-'    |           http://redis.io        

  `-._    `-._`-.__.-'_.-'    _.-'                                   

 |`-._`-._    `-.__.-'    _.-'_.-'|                                  

 |    `-._`-._        _.-'_.-'    |                                  

  `-._    `-._`-.__.-'_.-'    _.-'                                   

      `-._    `-.__.-'    _.-'                                       

          `-._        _.-'                                           

              `-.__.-'                                               

1168:M 07 Apr 13:13:01.388 # Server started, Redis version 3.0.6

1168:M 07 Apr 13:13:01.413 * DB loaded from disk: 0.025 seconds

1168:M 07 Apr 13:13:01.413 * The server is now ready to accept connections at /var/run/redis/redis.sock 

if I try redis-cli commands even wit the -a password -p 0 gives always connection refused

BTW I am not a linux professional and don't know what aditional info you need

Thanks for any help

[Heinz E. Silkeit]

I have another information ....

after an update I have got that message and than again every 15 Minutes that message from 1st post.

RedisException: Redis server went away at /var/www/nextcloud/lib/private/Memcache/Redis.php#54