I install the new Lion on my 27-inch Mid 2012 desktop Mac and have been having perpetual issues with the WiFi dropping. I have tried all the fixes I could find and none seem to work.
One item suggested it could be modem – but it appears to be new (802.11n). Working with a strong signal – and it has no problems with my Mac Air running the same OS.
Help! This is so frustrating. I can go to the network diagnostics and bring it back each time but I have to do this 10 – 15 times a day.
MAC OS 10.7.4 Wi-Fi Problems
Hi,
Upon reviewing your concern, it seems that your MAC's Network connection drops unexpectedly. Below are the steps that I believe might help you resolving your concern.
1. Check your range to your active WiFi router and then kindly reduce the effect of interference. Because if your computer ifs too far from your WiFi router then it is possible that your computer may not detect your WiFi network properly. Make sure that your computer and your WiFi router closer together and make sure that there are no obstructions such as walls, cabinets, and so forth.
2. Also, you may try to your computer to other WiFi network to make sure computer's network works fine. If the connection push through to other network connection, then the issue you are having is related to your Network router or your ISP (Internet Service Provider). In that case, I may recommend that kindly contact your ISP to troubleshoot your Network connection.
Also, you may follow these steps if your computer doesn't automatically connected to your desired WiFi Network. Kindly click the link below:
Troubleshooting Wi-Fi issues in OS X Lion and Mac OS X v10.6
Hope this might help. God Bless.
MAC OS 10.7.4 Wi-Fi Problems
Hi
First you can try these tips. Turn wireless on & off > Reboot the MAC > Restart the router.
Secondly, access through system preferences > networkÂ
Set a manual IP address with DHCP, Move WiFi to the top of the service order list, Move the primary router to the top of the 'preferred network' list, Detect existing WiFi connection and re-add  them, Add a extra DNS entry, Add a new network location.
Thanks