Can't get Redis to work with WordPress on Vserver running Ubuntu 20.04.4 LTS

Hi,

I´m struggeling to get Redis to work with the Redis Object Cache plugin for WordPress and hoping someone can give me some advice.

For me it seems Redis is working correct:

When trying to activate the Object Cache in WordPress this fails:

It’s the well know Connection refused issue … but I don’t see why as Redis is running.

Status: Not connected
Client: PhpRedis (v5.3.7)
Drop-in: Valid
Disabled: No
Ping: 
Connection Exception: Connection refused (RedisException)
Errors: [
    "Connection refused"
]
PhpRedis: 5.3.7
Relay: Not loaded
Predis: Not loaded
Credis: Not loaded
PHP Version: 7.4.29
Plugin Version: 2.0.25
Redis Version: Unknown
Multisite: No
Metrics: Disabled
Metrics recorded: null
Filesystem: Working
Global Prefix: "u1b9Tti_"
Blog Prefix: "u1b9Tti_"
Global Groups: [
    "blog-details",
    "blog-id-cache",
    "blog-lookup",
    "global-posts",
    "networks",
    "rss",
    "sites",
    "site-details",
    "site-lookup",
    "site-options",
    "site-transient",
    "users",
    "useremail",
    "userlogins",
    "usermeta",
    "user_meta",
    "userslugs",
    "redis-cache"
]
Ignored Groups: [
    "counts",
    "plugins",
    "themes",
    "blog-details",
    "blog-id-cache",
    "blog-lookup",
    "global-posts",
    "networks",
    "rss",
    "sites",
    "site-details",
    "site-lookup",
    "site-options",
    "site-transient",
    "users",
    "useremail",
    "userlogins",
    "usermeta",
    "user_meta",
    "userslugs",
    "redis-cache",
    "blog_meta",
    "wordfence",
    "wordfence-ls",
    "avada"
]
Unflushable Groups: []
Drop-ins: [
    "advanced-cache.php v by ",
    "maintenance.php v by ",
    "Redis Object Cache Drop-In v2.0.25 by Till Krüss"
]

Any advice is very welcome. Thx a lot in advance
Michael