I just realized that any link from Roblox (HTTPS) will throw this error going to here (HTTP).
I assume this can be fixed by moving to HTTPS here also, so I figured I should bring this up now rather than later.
(This behavior only occurs if HTTP or HTTPS is included in the link)
As far as I know, roblox doesn’t host it themselves, mainly because when discourse had outages at their hosting, this forum was down. So they would have to either 1. host it themselves, and add SSL, 2. contact them, and set it up.
Just ran into this issue myself. I was trying to link a public thread to the ROBLOX forums (Scripters), but even though I put http:// instead of https://, the site kept turning the link into https://. I had to tell people to manually remove the s from http to visit the thread.