Just another day
Expect many thousands of intrusion attempts a day for an address with a domain name. The worst bot armies are smart enough to evade adaptive firewalls by having hundreds of bots attempt only four or five attacks each per day.
Your best bet for a tiny server is to determine which networks have the most bots and hackers then block them. My small business router pretends that nobody's home when Taiwan, China, or S. Korea calls because they'd otherwise saturate my computer and bandwidth. Anything mentioning "yahoo" to my mail server gets rejected so there's no need for a trip to a Spamhaus to confirm that it's junk. I occasionally sift through what remains and send out abuse complaints when it gets bad. An invalid network abuse contact gets the network in the firewall.