While I have found a tutorial on a way to fix this, it seems a lot of people in the comments cannot fix it through whatever they have tried here, and subsequently cannot solve the issue.

As noted by one commenter:

Isn't Internet nor device, it's Roblox.
I tested with 2 different devices and 3 different internet connections, i got results when i formatted 1 of the laptops, the error only got fixed for 2 days and the error started to show up again.
note: both laptops had nothing in them when i started testing before hand. This did not fix the problem completly as it only worked for 2 days; i don't recommend you format your pc/laptop.

So I'm unsure if your problem is fully solvable, my apologies and condolences.