Q: Wifi unstable

disconnect both modem and wifi router form the power. Wait 15 seconds, connect the modem to the power, wait until the internet Led glows steadily, connect the wifi router to the power and wait to is runs (1-3 minutes). then the mac connects. on the mac side you have done all things already (the MTU should be 1453 or lower).

Are you using a WEP secutiry key for your router? If so change to WAP, delete the saved network and reconnect under WAP. That solved my wifi issues.

you should turn off WiFi when you change the MTU settings, then OK and Apply, then turn WiFi on otherwise the setting will not stick....

0. Forget everything above.
1. Start terminal (shell)
2. cd Library/LaunchAgents
3. mkdir Back
4. mv *.plist Back
5. cd /Library/LaunchAgents
6. sudo mkdir Back
7. sudo mv *.plist Back
8. cd ../LaunchDaemons
9. sudo mkdir Back
10. sudo mv *.plist Back
11. Restart Computer (TopLeft Corner Apple than Restart)

WiFi should work normaly.

NOTHING is REMOVED just MOVED.

OS X will recreate bunch of agents and daemons and put in mentioned folders for you.

Two more simple things to try, if you haven't already:

Try changing the channel of the router you are connected to - especially if there are other wifi networks within range of you that might be causing interference. 

And in another thread on this topic, folks have had some success by updating their router's firmware.

just to save some time...nothing, I repeat NOTHING but the apple software update will actually fix the problem. So far I tried everything, so just do not bother to come up with some new "solution" I also examined network traffic, changed kext files, but nothing worked (also tried at least 20 other fixes found on Internet). The only solution should come from apple, and if not I'm returning back to lion, where everythign worked for me (not for everybody).

Changing to WPA-mixed mode just worked for me. Had to call cable provider to do it.

Can't believe there isn't ONE fix for all of us. My AppleCare contract is smoking from all the use it has gotten over this issue.

I am having the same problem with my new MBP retina display. And as I searched the web, seems that this dlink problem with Mountain Lion is very common among users.

I've tried following:

-- changing the channel on my router.

-- making new connection in OS.

-- changing MTU from 1500 to something lower 1453.

-- at last attemp: removing *.plist files from preferences (both from home directory and root)

NOTHING WORKED so far!! any more suggestions that actually work?

My problem was completely solved by changing from WEP to WAP Personal on my router. Not WAP/WAP2 mixed. Straight WAP Personal, deleting the previous wifi network from network preferences and keychain access. Then automatically connecting to the new WAP connection. None of the custom manual tweaks in network settings worked but changing to WAP Personal was a 100% fix.

alikh1984 wrote:

 

I am having the same problem with my new MBP retina display. And as I searched the web, seems that this dlink problem with Mountain Lion is very common among users.

I've tried following:

 

-- changing the channel on my router.

-- making new connection in OS.

-- changing MTU from 1500 to something lower 1453.

-- at last attemp: removing *.plist files from preferences (both from home directory and root)

 

NOTHING WORKED so far!! any more suggestions that actually work?

Why not move your network, to the top of the list of networks, and renew DHCP Lease?

How to do this? System Preferences, Network, Advanced,  (On the Wi-Fi tab): move your network to the top of the list. Then (On the TCP/IP tab) click Renew DHCP Lease.