Could you explain how to connect my Backend to Redis via internal network?

I'm connected via Public Networking now and it works. But i can't connect through internal and get error

[ioredis] Unhandled error event: Error: getaddrinfo ENOTFOUND redis-dev.railway.internal at GetAddrInfoReqWrap.onlookup [as oncomplete] (node:dns:109:26)

To postgres i'm connect without problems via internal links.

Thanks for answer.