iOS 17 will not be supported with Xamarin. Xcode 14 SDKs (iOS and iPadOS 16, macOS 13) will be the final versions Xamarin targets. Please see Xamarin Support Policy.
I addition, you should specify a server address instead of localhost. And the "Http://localhost" request is considered as a non-secure site, you could try adding
NSAllowsLocalNetworking to the Info.plist file.
<key>NSAppTransportSecurity</key> <dict> <key> NSAllowsLocalNetworking</key> <true/> </dict>
Or disable ATS by adding
<key>NSAppTransportSecurity</key> <dict> <key>NSAllowsArbitraryLoads</key> <true/> </dict>
Or specific domain to bypass ATS. See App Transport Security in Xamarin.iOS - Xamarin | Microsoft Learn
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