system
Given the following post, respond as if you're commenting on Reddit:
human
If you hypothetically were able to time travel a completely up to date phone 3-5 years ago, how much of it could actually function (different apps/social media) on the “past internet “
gpt
Your web browser should basically work fine. Browser vendors are usually very careful to maintain backwards compatibility, which means newer browser versions should always work correctly with old versions of websites.

One caveat is that you might have issues connecting to sites using HTTPS. To verify that the connection is secure, the browser needs to see a chain of digitally-signed certificates, ultimately linking to a certificate authority that the device trusts. Since each certificate is only valid for a certain period of time, you would need to make sure the clock on your device matches the time you've traveled back to. And even then, you might run into difficulties -- the set of certificates that were trusted back then may not be the same ones that are commonly trusted now, because CAs start up or go out of business every once in a while.

Installed apps might be a different story. Apps typically communicate with their back-end services using undocumented protocols that could change from version to version. If the app developers are competent, they should be ensuring *forward* compatibility -- that is, users who are running old versions of the app (because they haven't updated) should still be able to communicate with newer versions of the server. But they might not bother to test for backwards compatibility, because normally it would never be possible for someone to be using a newer version of the app before the corresponding server software has been deployed.

But since the exact protocol details are usually not released outside the companies that develop the apps, there's no way to be sure which ones would encounter problems, or how severe those problems would be.