I've been wanting to take a shot at updating Arachne and/or some other web software for MSDOS to be able to surf the modern web. Maybe even access twitter or ebay.

The problem I've come across before even getting started is that everything now has massive encryption security to access... https, TLS, etc.
While the protocols could probably be written to run on (some) vintage dos hardware, handling the encryption/decryption would take forever, if the retro computers could handle it at all.

So I got to thinking about this scenario:
I have my "modern" computers on my network, connected to my main router-> cable-modem-> internet.
I was thinking of setting up a secondary network with an older router. That older router would connect to the newer router.
I would then have a modern computer, maybe a raspberry pi, even... handle the encryption/decryption, then pass on the unencrypted traffic to the retro computers connected to the older router.
It would take the unencrypted traffic from the retro computers, encrypt it, and pass it on to the main router; it would then receive the encrypted traffic from the main router, passed through the old router, decrypt it, and pass it on to the retro computers, who could then, as best they were able, run Arachne or other open source web software that would display the unencrypted data, say a (mostly) http5 compliant web page or email.

I'm sure there's a lot wrong with this idea, which is why I bring it up. Granted, one will almost certainly not be able to access twitter or a modern website with an IBM 5150PC... but they might could with a 486.
As I recall when I was learning http decades ago, it's designed for the browser to ignore tags it doesn't recognize. Is that still true?

Anyway, does anyone have any thoughts on this idea? Ways it might work?
I came across this software mitmproxy https://mitmproxy.org/ that suggested to me that what I want might be possible... at least as far as the encryption problem.