hatters1976 :
The file downloaded in your set-top box probably does not contain the 7-zip file format header. This means that the HTML code and not the file was probably downloaded.
The algorithm of the plugin, intended for the verification of the header of the 7-zip file from the source Chocholousek with picon-packages, is here:
So, as it is obvious according to this algorithm, the downloaded file in your set-top box is probably not really a 7-zip file, but rather some HTML file.
If there is a .7z file with picons in the "/tmp" folder of your set-top box, check its contents. For example, copy this file via FTP connection to your PC and open it - in some text editor or in some so-called "hex-editore" (tool for editing disk contents). There must be a header for 7zip files at the beginning of the file, and there should also be no HTML code inside the file, but archived and compressed code from various .png files.
This "error" (server protection) occurs primarily when the client tries to connect via a VPN network. Unfortunately, the VPN network is often misused for various attacks... so that's why the VPN network is not allowed and rejected by the server and you will only get an HTML code with a message (rejection).
It can also be about banning your IP address, on which someone probably tried to perform DDoS or other attacks (loading the server with repeated and very fast and frequent accesses to packages with picons).