Error: No alive nodes found in your cluster

Hi, I had File with Tika and Elasticsearch running cleanly as a Docker Compose on a LXC under Proxmox for a few weeks now. Full text indexing was running.

Now I have - based on a recommendation - discontinued the LXC and run the whole Docker containers now under Proxmox on a VM.

All docker-compose.yml files and related folders are on my NAS. This is connected to the VM via NFS. So I didn't have to do anything else than boot the VM (running Ubuntu Server 20.04 LTS), put updates on it, installed Docker and Compose, ran a PULL of the Docker containers and started the Docker.

Filerun also runs clean, but when I press the test button in the backend under "Search", I now get the message "Error: No alive nodes found in your cluster". As far as I have read, the user of the elasticsearch server must have write permissions on the folder "esearch".

In my LXC environment it says 1000:1000 esearch.

In my VM environment (my user is called linus) it says linus:linus esearch in the same place.

But a sudo chown -R 1000:1000 esearch does nothing, it does not change.

Here the part of elasticsearch in dockere-compose.yml

elasticsearch:
#image: docker.elastic.co/elasticsearch/elasticsearch:6.2.4
image: docker.elastic.co/elasticsearch/elasticsearch:6.8.13
container_name: elasticsearch
restart: always
networks:
- intranet
environment:
- cluster.name=docker-cluster
- bootstrap.memory_lock=true
- "ES_JAVA_OPTS=-Xms512m -Xmx512m"
ulimits:
memlock:
soft: -1
hard: -1
mem_limit: 1g
volumes:
- $PWD/esearch:/usr/share/elasticsearch/data
ports:
- 127.0.0.1:9200:9200

Here I need some help. Thanks a lot