How to enable Redis Cache via Unix Socket on HumHub

First of all, you will need to enable your Redis instance via cPanel. You can follow the instructions here: Enable Redis Unix Socket

Redis can be implemented as UNIX socket by using syntax similar to Craft CMS

You'll want to edit protected/config/common.php to reflect:

return [
'components' => [
     'cache' => [
          'class' => yii\redis\Cache::class,
          'defaultDuration' => 86400,
          'redis' => [
                'unixSocket' => '/home/USERNAME/.kxcache/redis.sock',
                'database' => 0,
          ],
       ],
    ]
];

Check that protected/config/dynamic.php doesn't have useApcu key defined for caching, and instead the Redis yii caching class for the cache configuration (components -> cache):

    'cache' => [
      'class' => 'yii\\caching\\Redis',
      'keyPrefix' => 'humhub'
    ],