I had some difficulties when installing node-red on a synology server thanks to docker.
The main problem : the node-red instance does not use any dns server by default.
I managed to map /etc/resolv.conf of the container with a custom resolv.conf, but after that, the container can not communicate with another container easily.
In my case, i want to use in Node-red another container influxdb by its "influxdb1" name, but influxdb1 as a hostname was not found by node-red with a mapped /etc/resolv.conf.
I had to re-create a node-red container with the -dns parameter for the command line.
(impossible to update this setting after the container is created)
1 - Download Image
2 - Create a "data" folder
3 - Configure the node-red container
DO NOT FORGET THE --dns 220.127.116.11 --dns 18.104.22.168 as parameters !
Protect admin node-red with user/password
launch a "bash" terminal window
go to /usr/src/node-red/node_modules/node-red-admin/
start node-red-admin with "hash-pw" as a parameter
type your password, note the hashed version :)
modifier the "settings.js" in the mapped /data folder