I’m not aware of any negative symptoms but I see similar errors like the one below. It seems there is “confusion” or site name mismatch in some requests.
2025/04/02 10:40:29 [error] 555#555: *410822 connect() failed (111: Connection refused) while connecting to upstream, client: 10.1.22.24, server: myERP.myDomain.com, request: "GET /socket.io/?EIO=4&transport=polling&t=PNsyaee HTTP/1.0", upstream: "http://127.0.0.1:9000/socket.io/?EIO=4&transport=polling&t=PNsyaee", host: "site2.otherdomain.com", referrer: "https://site2.otherdomain.com/app/doctype/Service%20Task%20Template"
My upstream Nginx server is a separate machine at 10.1.22.24.
Has anyone seen a similar error, or do you have any suggestions what might cause this error?