Macbook Air Network Problem Caused by Firewall Setting on Router

[stofect]

Recently I moved to a new apartment and found that the wifi network is very slow on my macbook air (mid-2011, with Mac OS X Mountain Lion), but all other devices including Windows PC, iPad and iPhone are normal.

Then I connected the Macbook Air to the router with a USB network adaptor and ethernet cable, but still very slow, quite strange. Also, I booted to Windows via boot camp, also very slow.

I googled it, and found many people have similar problem, but no solution...

Because it happened to my macbook only, and I think it is some compatibility issue between the router and macbook air. The router is from motorola and I think it is a cable modem.

Finally, I decided to change some settings in the router, to check if it possible to solve the problem. Finally, I found it, the firewall setting.

By default, the firewall protection is enabled. After I disabled it, problem solved.

I share this experience and it may help someone else. And I also wonder that does anyone know the reason?

BTY, I live in Mexico City now.

[Mrbobb]

OK...

So I assume those are the current settings that work?

What are the old (no work) settings looked like?

[stofect]

It is old setting, the new setting disabled firewall option.