I was misguided by the network policy of the office when I try to determine whether the target port of target server is open

I wish the access to 3306 port of the target server was blocked from the internet, but when I test it from my computer and a server in the test environment, it shows the port was open, the test by my co-worker in the other office shows the opposite result. I find out that I change the port to number that definitely have no service use it, or change the ip that may not been owned by a server on the internet, the result is still open, I realise that the network policy of my work place is nothing like I've been used to.