Conclusion with IPB: (good)

 Sn8_gTEdSJqNWRWVKydwFQ.png You have insufficient rights to see the content.

Conclusion with YAF: (bad)

 tR4D1jE2TzeQKrj4th2P8Q.png You have insufficient rights to see the content.

https://www.codeproject.com/Tips/895727/Consume-an-RSS-Feed-in-an-ASP-NET-Web-Page 

Added to YAF/pages/forum.ascx for the test

<%@ Register TagPrefix="YAF" TagName="News" Src="../controls/News.ascx" %>
<YAF:News ID="News" runat="server"/>

Sorry but we can not help you with custom code

<YAF:News ID="News" runat="server"/>

that part of code is not part of YAF. And you don't post here any code to help you. Instead of using code you could try to use widgets instead for example

https://feed.mikle.com/ 

<YAF:News ID="News" runat="server"/>

Good evening. I would not like to use extraneous widgets ... Is there an opportunity for the forum to display news from this topic on a kastum? In the first message, I published a link to the code that works and was successfully added to the forum. But unfortunately it does not work with the threads of the YAF forum itself.

It is necessary to understand for what reasons we receive an error using a link of the form: http :// www .yetanotherforum. net/forum/rsstopic/ft0-forum-rss?pg=3

If we use a link like: https ://lenta. ru/rss/news that all works flawlessly.

 rss.PNG You have insufficient rights to see the content.

You have not provided what that control

<YAF:News ID="News" runat="server"/>

actually does, or any code

<YAF:News ID="News" runat="server"/>

I'm sorry, it's working. In view of the fact that in this forum my IP address is regularly blocked - I received this error ...