There is some confusion here. The main scope of re7zip is not to provide a pretty GUI. In fact, if you look on the screenshot for the program you will see the recommendation to only use the command line.
The main scope is to extract files from archives on the Internet and this feature has been reported as working for different cases.
If in one situation is not working, this might not even be something related to the tool. Might be some configuration on the server side that limits the HTTP connections, time-out parameters or some other detail. The URL is not even provided on the topic post.
I'm unable invest further effort to investigate this matter. As said, I'm working in other projects right now and the code is available for any other kind soul to propose improvements.