同僚は問題なく Apache Axis でプロキシを作成できました。
残念ながら、デスクトップ用の VS 2012 Express にしかアクセスできません。
サービス参照を追加しようとすると、次のエラーが発生します。
There was an error downloading 'https://app.hostname.com/services/APP?wsdl/$metadata'.
Unable to connect to the remote server
A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond 123.456.789.123:443
Metadata contains a reference that cannot be resolved: 'https://app.hostname.com/services/APP?wsdl'.
There was no endpoint listening at https://app.hostname.com//services/APP?wsdl that could accept the message. This is often caused by an incorrect address or SOAP action. See InnerException, if present, for more details.
Unable to connect to the remote server
A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond 123.456.789.123:443
If the service is defined in the current solution, try building the solution and adding the service reference again.
反対側の開発者から「私にとってはうまくいく」という扱いを受けていますが、残念ながら、質問する適切な質問やこれを解決する方法がわかりません。