Just don’t run broken software. The attackers will not be able to exploit you then. If they have zero day exploits, the WAF will most of the time not save you since they are often pretty easy to circumvent. WAFs are only effective against old and shitty exploits that should be patched anyways since ages.
Welcome to the internet. You will be probed. Just as your immune system, or rather your body, is being probed.