hi i am trying to setup my yahoo account info. I keep getting an error message apple.imap.mail.yahoo.com is not responding. I went to an apple store today and i was able to do it through their wifi. wifi at home does not work, please help

Hi, I bought the new Ipad, I finished setting up everything but my Yahoo Mail. I enter account info and I get an error reading"the IMAP server, apple.imap.mail.yahoo.com is not responding. check your network connection and that you entered the correct information in the incoming mail server field." I went to an Apple store today and I was able to enter my info with no problem through their WIFI. I was able to pull up my email. I went home to try it, I am now home and I tried to log onto my email thru my WIFI at home, and I can not get it to work. I have an IPhone also that works thru my WIFI no problems. I was told by the tech, at the apple store if I had a problem at home that I would need to go into my settings in my router to "port forwarding" but I can't figure out what I need to disable or enable. I don't understand why it won't work. Please help me thank you.