I used version 9 & 10 of FeedReader to connect to the URL "https://rss.mediafeed.nl/mediafeed.xml".
In all cases I get a login screen. When Uname & Pword is filled in I get for each alternate connection attempt two different messages:
1. Error connecting with SSL.
2. Connection closed gracefully.
This connection and the same configuration settings for the Proxy worked briefly on 2 occasions. The Proxy server was not touched between test good and the failing sessions sessions.
The product "RSSFeed" was used to test the connection and that worked OK.
I have made an Ethernet trace with WireShark and that is available.