You are correct that this is caused by a change on our side, related to the implementation of HTTPS. All websites are expected to have HTTPS nowadays, so the changes had to be made. Because of this, the URLs must match in order to prevent cross-origin issues.
Please update the embed code on your website as per the email I sent you and let me know when you've done that.
I did receive your email actually.
It appears that your problem is the same.
You need to change the embed code in your website, from this:
guptachat <script src="http://guptachat.826.n7.nabble.com/embed/f1"></script>To this:
guptachat <script src="http://gupta-chat-more.826.n7.nabble.com/embed/f1"></script> -------
The general solution:
(If your forum requires users to log in to read the forum, you will need to be logged in to see this)
In the top left of your site, there is a link to the root of your forum. You can copy that link and replace the existing urls in the embed code with the updated domain.