Firewalls rely on "SSL Inspection." To inspect traffic to sites.google.com , the firewall would have to break Google’s HSTS (HTTP Strict Transport Security). Modern browsers will outright refuse the connection, throwing a security error. Most Network Admins whitelist Google entirely.
If you need a quick unblock, look for a shared Google Site config. If you need security, build your own private Nebula network and use Google Sites as your landing page. Just remember: with great power comes great responsibility—and Google’s ban hammer. nebula proxy google sites
Furthermore, Google occasionally sweeps its own platforms, deleting Google Sites that violate its Terms of Service (specifically regarding the circumvention of access controls). Firewalls rely on "SSL Inspection
For a faster, more secure proxy, you need to host the Nebula PHP backend elsewhere, then embed it via Google Sites. If you need a quick unblock, look for
Your traffic goes: You -> Google Site (to get config) -> Nebula Lighthouse (encrypt) -> Target Website. This adds significant ping (lag). Fine for text, terrible for gaming or video calls.