There are some services that I expose to the internet (using Apache reverse proxy) that really should be accessed by only a small set of devices. Requiring client certificates seems like a great way to reduce the attack surface and prevent brute force attacks (since the attacker doesn’t even get a chance to attempt a login).
I wonder about the difficulty on the client side as well as other practical implications. The clients are smartphones of various makes.
I have been thinking about it until I realize that nginx still can have zero days vulnerabilities that could be even in the tls layer or so and decided to actually close the port completely in the Firewall and just run Wireguard on devices. And as fallback I have external program that have a webbserver with qr code with link and ip query encrypted so when i scan it on smartphone i have to follow the link to internal server that i only can access with Wireguard so then only that public ip is then added to my Firewall rules temporary.