Never used snap chat. But I believe there was a problem reported on here yesterday with a sky broadband customer so could be related. If so the problem lies at sky's end.
Ask SC support to check if your ip is blocked. You can prove this by trying on mobile data Vs wifi.
I have no affiliation whatsoever with O2 or any subsidiary companies. Comments posted are entirely of my own opinion. This is not Customer Service so we are unable to help with account specific issues.
Currently using: Pixel 7a (O2 & Lyca), One Plus 6 (Sfr), iPhone 12 Pro Max (Vodafone)