internet sharing doesn't work

I have the same issue (just posted another discussion). When I had Snow Leopard, I set up internet sharing on my iMac and could then connect my MacBook to the internet via the wi-fi link. When I downloaded Lion a few months ago, it messed up internet sharing, but if I re-set the option in the iMac system preferences each time I logged on, it would work until the next time I logged off. At the time Apple admitted it was a bug. I've just discovered this work around isn't working, so like you, hoping someone will find the solution.

Ugh...nevermind. My fix enabled me to log on, but the connection is unresponsive.

Message was edited by: joshua413

Weird... Yesterday I had the same problem, I was not able to use internet sharing from a MacBook Air 11 with Mountain Lion (connected to the net by USB Ethernet adapter) to an iPod Touch and an iPad 3. The wi-fi link was established, but no internet connection... I have another MacBook Air (13), with that one everything worked great. Today I booted up the MBA 11 and, much to my surprise, the internet sharing works as it should.

I have no idea of what's going on!

I am having the same issue. Internet sharing worked great before upgrading to Mountain Lion. Now, my other devices (iPhone, iPad, and Macbook Air) recognize the wifi from the Mini, but there is no connectivity with any of them. Apple needs to get on this!

Looking around, it seems like the issue affected some when the Lion upgrade happened, but I have not seen any resolution. Lion was ok for me, but ML threw everything off.

I think it means I have to purchase a wireless router because I use my iMac as the base station (Internet Sharing) for everything at home (apple TV, iPhone, iPad, etc). Now, the iMac is the only thing that is connected and my kids are hounding me to get the Apple TV working again so they can watch their movies. Having to go out and spend money on extra hardware after upgrading seems a bit on the ridiculous side...at least my wife thinks so. 🙂

Does anyone out there have any fixes? Or should I buy a router?

On your Internet sharing options, try setting it to channel 11.

Also try with and without WPA2 security.

Thanks...I will try that when I get home. Question...why are all the other security options now gone? I don't remember what they were, but before the upgrade there were 4-5 different options.

If you see the gray wifi icon on your menubar (with an arrow), but your iPhone does not have internet connectivity, on your iPhone go to Settings > wifi > your internet sharing connection (click on the blue arrow at the right) > click on DNS > type 8.8.8.8 (this is google DNS).

if you see a hollow wifi icon, disable WPA2, only way to make it work (useless, I know).

Have you tried just rebooting the iMac?

As I reported a few posts earlier, I had the same problem after upgrading to Mountain Lion (wifi ok but no internet connection), but the day after I rebooted and Internet Sharing worked again as a charm...!

Hope you can find a solution soon!

They're right there, in the Internet Sharing option. Stop Internet Sharing and you will be able to click on the options button.

Here is a screenshot...only the two options available. On my iMac and my Macbook Pro (both upgraded). I don't remember what all the other ones were...but they are gone.

Yes, those are all the options. If you click on WPA2 you will be able to set the password.

In my experience, with WPA2 enabled, Internet Sharing won't work (hollow icon on menubar) or will work (gray icon) but will require setting DNS on the iPhone as I explained before.

Of course, with WPA2 disabled, anyone will have access to your Internet connection, this is not good.

The Channel 11/WPA2/reboot suggstion didn't fix the issue for me.

I had the same problem - until upgrading to ML Saturday night, my 3GS could connect by wi-fi to my Mac Mini. This has wired ethernet to the router.

Then with ML, it was either not connected to, or can't connect to the internet (because of the dreaded "self-assigned IP address: 169.xxx etc." that kept replacing my alterations ).

There are numerous suggestions, mostly pre-ML, which refer to .plist files that don't seem to be in ML. And complicated.

IN "System Preferences -Network" I tried numerous "new" networks, which didn't work.

What did work was: choose to create a new wi-fi network, and choose "Advanced". Give it a name in "Wi-fi", in "TCP/IP" choose configure IPv4 manually, with address 10.0.0.9 and Subnet Mask "255.255.255.0". In "DNS" I put the server numbers of OpenDNS, which I connect through - these would be the DNS numbers your router uses, otherwise (I think).

This didn't actually make it work. But, in "System Preferences -Sharing", Internet Sharing was ticked. I unticked it, and curiously got a pop-up warning saying that if I turned ON "internet sharing" other computers could share my internet connection (even though I'd just turned it OFF).

Turned it back on by checking it and went back to "Network" where the Wi-Fi Network name says "Internet Sharing: ON", and the details in "Advanced" that I entered are still there ("self-assigned IP address: 169.xxx etc." cast into outer darkness).

My 3GS now connects to the internet, as it did with Snow Leopard, the downside is that sleep isn't as deep as it was before - external HD light and Macally mouse LED stay on, even though "Wake for network access is unchecked in "Energy Saver"/

I did enter these details in the iPhone "Wi-Fi Networks" Static part, but now they are showing the IP address as 192.xxx.2.2, and the same in Router and DNS (but .2.1). This may not be necessary as it is DCHP that is now highlighted.

I am having the same issue. Internet sharing was working great before upgrading to Mountain Lion. Now, my other devices (iPhone and iPad) recognize the wifi , but there is no connectivity with any of them. Apple needs to get on this ASAP !