I've been trying to follow these instructions exactly as written* to get an iPhone 14 Pro Max with iOS 17.5.1 connected to my router.

https://www.tp-link.com/us/support/faq/3447/

I've followed them carefully and repeatedly. I've checked and double-checked.

A connection cannot be established — it always fails within a second or two.

If I then disable VPN and try again, it takes a lot longer to fail with an error indicating the router wasn't listening. So it seems the phone and router can converse; they just can't agree on something.

I would love to see whatever the router might be logging about the handshake failure, but I can't find a log which shows that.

* …with the exception of the router's IP address of course — the phone and router are on the public internet and the router has a public host name.