Could not setup mqtt backend

I finish setup Lora Server ,Lora Appserver and Lora Gateway Bridge but i found this problem it said that "level=error msg="could not setup mqtt backend, retry in 2 seconds: Network Error " by the cmd journalctl -u lora-gateway-bridge. i try to find out what it happend i am very begginer please help thank you.

A post was merged into an existing topic: Could not setup mqtt backend : retry in 2sec : network error: connection refused