Hi Zhifang Wang
We're running a clean install of GIS Enterprise 10.7.1 Dev Portal and I've just created that Hydrant Inspection app using the template provided.
The issue above was that the CORS settings url was slight wrong. Restrict cross-domain requests to ArcGIS Server—ArcGIS Server | Documentation for ArcGIS Enterprise
We also added https://survey123.arcgis.com to the cross domain settings within the Portal security settings.
So we got the survey123.arcgis.com web app working successfully with our behind the firewall Dev Portal.
Our next problem we hit was that the Survey123 mobile app wasn't able to connect via our F5 VPN on our iphones to the portal authentication even though Explorer worked all OK. We're talking to our local ESRI support and our internal cybersecurity to work out what is going on. It might be that Survey123 is sending traffic outside the F5 VPN.
We might be having similar issues with Collector also, though Collector is authenticating OK with Portal, it's not listing any Collector maps even though we're sure we've got Collector compatible maps - with "Use in Collector for ArcGIS" ticked.
Thanks,
Peter
Peter T, Brisbane