Internet really slow after upgrading to Lion from Leopard!

On the same day, I upgraded my 2009 iMac and MacBook Pro to Lion. Internet on iMac sluggish, as others have reported, whether using wifi or ethernet (tried the vpram, et. al. reset, to no avail). MacBook perfectly fine, using wifi from same airport router. For example, tried to upgrade my iPhone software yesterday by connecting to the iMac. Said it would take hours to download, and failed on multiple attempts. Hooked the iPhone to the MacBook, and it sailed through in about 8 minutes total. How can the internet be so normal on the laptop and so horrible on the iMac?

I have the same issue. I had no problem before Lion - immediately after upgrading my internet connection has slowed to a crawl. As with others, you tube is impossible. I've stopped using Safari in favour of Firefox and Camino and they are faster, but still not fast enough for anything media rich like video and music.

(BTW: I connect via wifi through a Thompson modem).

The weird thing for me, and this seems different for most other people's experience, is that this is affecting my MacBook pro as well - which is still running Snow Leopard. The fact that both Lion and SL macs are experiencing slow internet says to me that this is a modem issue.

So I've tried a few of the fixes suggested by others - like resetting the modem to the factory defaults; tried channels 1 to 13 on the modem; renewing the DHCP lease, plus tinkered with a few other things, and... all to no avail. I've tried turning wifi off on the MacBook while connecting with just the iMac, and using ethernet instead of wifi... no difference.

So I'm going to try a few more:

1. JMLA's fix of deleting my network from the preffered list then creating a new one.

2. Open/Google DNS

3. Resetting the PRAM and NVRAM like anniebobannie suggested.

I'll let you know how I get on. If they all fail, I'm going back to Snow Leopard unitl I hear Apple have fixed this properly.

The frustrating thing is I love everything else about Lion. Even reverse scrolling! But slow internet is affecting my business, so without a fix I've no option. [Frustrated!] 😠

You mentioned other browsers are better. I'm wondering if this is a Safari/WebKit issue? That would explain why it's also affecting Snow Leopard, too. Safari 5.1 was released around the same time as Lion.

My performance problems seem to be gone, though, and I use Safari daily. I fixed permissions on the harddrive and that seems to have fixed a few of the strange issues that I was having. I also switched my Airport Extreme (older generation) to 802.11n and then back to 802.11b/g. Haven't been too concerned since.

I had the exact same problem - horrendously slow internet with lots of "time outs" and "server not found" messages. I did a clean install and everything is back to smooth sailing. When prompted, select "Reinstall Lion", then wait for the process to finish completely. Best of luck.

Okay, my slow internet issue is resolved 😀

But I'm still not % sure which fix did the trick. For anyone else out there having problems, here's what I did.

1. I deleted my network from the preffered list in Network prefferences, then used the assistant to set it up again, as recommended by JMLA. I did this with both my iMac, and my MacBook Pro. I then ran a test using Youtube (because it has been utterly unusable since installing Lion) and there was no change. Still buffering so slowly it was impossible. I was not amused.

2. I then reset the PRAM and NVRAM on both Macs (following anniebobannie's suggestion). Then ran a test again... and it was still no better. As you can imagine, I was pretty exasperated.

3. I woke up this morning, turned my iMac on and spotted an e-mail from a client with a linked Youtube movie (of an interview) she needed me to see. My heart sank. I thought, "now, I'm going to have to explain to my client why I can't view this interview." But I clicked the link anyway out of sheer bravado. It loaded and played in a flash - just like old times!

I've tried the MacBook Pro too, and both are working perfectly. The problem has gone away.

So I'm thrilled, but I'm not sure which one fixed the problem.

Seeing as the PRAM/NVRAM reset involves a system restart (and it was the second of the two fixes I tried) the system had by default been restarted after both fixes. This was at about 7pm Auckland time. By 11pm, my connection speed was still bad as ever, so had had almost given up. But now, this morning 8am Auckland time - it's all good. So it looks like it needed two reboots, with a full night's sleep in between!

So... thanks to both JMLA & Anniebobanie, between you, you've fixed my slow internet problem. I'm just not sure which one did the trick. Maybe 'both' is the answer.

Hope this helps anyone else out there having similar problems.

Mine is still not working. When it runs fast it is fast (i.e. speedtest.net will report close to my advertised cable speed every time, 11.3 mbps/0.940 mbps (12/1 service), but it is still laggy with the DNS or something.

I have tried removing and deleting and adding the network and resetting the P/NVRAM and about everything else. I am doing a clean install of Lion tonight and will report back.

Eric

Egads, I reinstalled Lion (format hard drive, clean install) and it is even WORSE. It is so slow it is almost unusable. Again, download speeds are fast, when they start. I reset the P/NVRAM again and it maybe helped a little. I think there is definitely a compatibility issue between my cable modem and OSX Lion. I wish I hadn't changed from DSL to cable at the same time as I changed to Lion, but since my Windows and even iPad and Android play nicely with the web I think it is mostly the fault of Lion. I forgot why I don't update until 10.x.2 or 10.x.3 usually 😉

Eric

Check out my post earlier regarding replacing DNS related files. I have a wired computer, not Wifi. Went from unusable to perfect with the patch and now weeks later without any problems, Better than reinstalling.

Yeah, I tried that before the fresh install and didn't help, also just installed it again afterwards and the internet is still slow. I boot the same machine into Win 7 and it works just fine.

FIXED!!!

Hey, I think I read it somewhere in one of your linked threads or maybe it was in this one (been reading too much stuff), and I disabled my routers firewall again (turned off IP Flood Detection and Firewall Detection), and my internet is blazing fast now. I tried this before and it didn't help, so it was probably a combination of one of the previous fixes (like the Zip from above) and the firewall fix.

For later reference I am running:

Zoom Model 5350 Wireless Cable Modem

I figured it was a compatibility issue between the two, as odd as that sounds.

What bothers me is why do I have to turn off my firewall on my router? All my other devices play nice with it. I will experiment more to see if it was the IP Flood Detection or the Firewall which was blocking it. I did enable the firewall on both my Mac's to make up for the router not having one, but I would prefer the router block.

Thanks for all the help,

Eric

Firewall is not active on my router and I'm sure not going to turn it off on the Mac. I've tried every fix offered in this thread. DNS still dies at regular but random intervals during the day. When it doesn't die, pages load at a snail's pace or time out. I'm forced to use my iPad, which has no problems even though it's using the same Time Machine wifi.

Apple is gonna have a tough sell with iCloud if Lion users can't even load Gmail.

Eric, just to cover all the bases, I'd suggest you check with the website of the people that made your cable modem (Zoom) and see if there's a new driver for Lion.

Best of Luck!

Fwiw, my T-W cable modem died just about the time I installed Lion and started have problems. I bought a new modem. Problems continued. Yesterday, I set it up for wifi and disconnected and powered off the Time Machine. Since then, everything has been fine. No apparent DNS drops, no loss of net access after waking from sleep.

One other difference I noticed: With the Time Machine, when I clicked the wifi icon in the menu bar, the "looking for networks..." spinner would be active as long as the menu item was open. With the other device, it goes away in about 5 seconds.

I just noticed a possible connection between slow internet and time machine. Lion on my laptop runs perfectly, internet fast as ever. I do not have time machine set to run automatically on the laptop. On my iMac, I do have time machine set to run automatically (to an external drive via firewire). On the iMac, sometimes the internet is fine, and other times it is dreadfully slow. The last time the internet slowed to a crawl, I happened to notice that time machine was backing up. I stopped the back-up, and the internet speed popped back to normal. Maybe some connection? Maybe this is an issue of time machine hogging resources?