I have an Archer C7 AC1750 router (Hardware version V2 and Firmware version 3.15.3 Build 180305) - and have been having problems with Spamhause who are blocking my IP address. One of the steps to solving this is to block port 25. I have found instructions here for blocking port 25 on a different router but the menu system is different to that on my C7 and I cannot find  the equivalent options although I believe the C7 may have a built-in firewall (?). Can someone give me (step-by-step) instructions on how to do this?

Thanks

P.S. Please ignore the reference to the A10 model if it appears in this post - my AC1750 was not listed in the limited number of wifi router options