Don’t pass the env var for grpc port, we already hardcode it as 33060 in the start arguments.
You just have to map port 33060 for access through the host. If you use docker network to access via container name as dns hostname, you don’t have to map that port in pydio-cells either.
If I recall correctly, the grpc_pass directive in nginx does not support variables unlike the proxy_pass directive. So you should use grpc_pass grpcs://pydio-cells:33060; instead. Keep in mind that if pydio-cells is not accessible when letsencrypt is starting up, nginx will likely throw an error and refuse to come up. I wasn’t able to figure out a way to mitigate it (that’s why we didn’t add the grpc info into the proxy conf for cells).
Also make sure that port 33060 is mapped in the letsencrypt container as -p 33060:33060.