Nginx plus unable to reach the AuthZero to echange auth code on '/ token' url

While configuring the Open id connect over nginx plus with AuthZero as IDP, we are facing the below error , what DNS resolver of other solutions are available

upstream server temporarily disabled while connecting to upstream, client: 10.3.31.252, server: , request: “GET /_codexch?code=If2ybDsIX6iBIXH-WJP_TMsOUXW36szltiEZXFAXH64-j&state=0 HTTP/1.1”, subrequest: “/_token”, upstream: “https://104.16.171.253:443/oauth/token”, host: “10.3.55.204:8010”
2022/11/16 07:32:46 [error] 19259#19259: *1 upstream timed out (110: Connection timed out) while connecting to upstream, client: 10.3.31.252, server: , request: “GET /_codexch?code=If2ybDsIX6iBIXH-WJP_TMsOUXW36szltiEZXFAXH64-j&state=0 HTTP/1.1”, subrequest: “/_token”, upstream: “https://104.16.171.253:443/oauth/token”, host: “10.3.55.204:8010”