Hi!

I am sorry if the question is not for here, please move it. I am trying to setup a hotspot with DD-WRT and the site from above, I want it to redirect to a certain page, which will contain a message and be named "index.html" but after that to not redirect again and to not need any agreement or anything, just to redirect to this page 1 every 24 hours or on connection.

 

Your question is not clear. To direct the hotspotsystem.com to your DD-WRT, you need to do the following:
1) The DD-WRT router must have a static public IP address that does not change. That is so traffic can be directed to it from the Internet
2) The owner of hotspotsystem.com has to edit their DNS records to point to that public IP address of the DD-WRT box.

Internet addressing is generally fixed, so whatever you set up, hotspotsystem.com will always go to the DD-WRT device. Only the DD-WRT device can do any re-routing or re-direction. To change where hotspotsystem.com points to is not practical, as propagating of DNS records through the Internet can take hours. You can't just flip DNS records on short intervals.