27" imac wifi problems (intermittant)

I am having the same exact problem. Bought a 27 inch iMac about a month ago, the wireless connection was a little slow off the bat, but then I was able to fix it. Recently after turning it on the signal is picked up fine for about 15 minutes and then all of a sudden the airport can no longer pick up any wireless network. Meanwhile my iPhone and MacBook have no issues. I called apple support and they had me complete a litany of useless diagnostic tasks - emptied my cache, did a hard reboot, repaired disk permissions , etc. None of it helped. Seems it's a hardware issue. Anyone know if this is a known issue with this model? I'm afraid the airport card itself may be defective in some way.

I think I'm having the same issues as both of you. This is on a new-to-me refurbed 21.5" iMac. WiFi works for maybe 5 minutes or so and then drops the connection. It's then unable to see my network or any other networks for that matter. I'm using an AirPort Extreme and everything works great with my existing MacBook Pro, iMac, Win 7, Ubuntu and even a Wii. It's got to be either a software/driver issue or a bad chip.

Hi,

I just took delivery of my iMac 27" i7 and was very happy - but am now less so (as I type this on a £250 netbook that has no problems at all). It appears I am suffering the same problems - internet up, then down, then up, then can't find the router, etc.

I'm somewhat dissapointed that issue can exist as every other wireless device I own, Iphone, etc. doesn't appear to have this problem, and after spending just short of £2000 on it I really didn't expect this kind of issue.

I'm going to go into the local Apple store this weekend and ask them about it, but I do hope Apple is reading this and will come back to us all with some indication of what's happening?

I have the exact same problem since 3 weeks. First weeks with iMac I had no problem, then it started as you describe it. Genius bar visit 1: Cache empty, reboot, etc.: no effect. Apple Care: channel change: no effect, Genius bar visit2: replace Airport extreme (....). I think it must be an heating or Airport card hardware problem. Any suggestions?
Thnx.

I've had no issues like this on my i5 iMac.

I did have a similar problem on a previous PowerMac G5 Quad where I had the local service centre install Wi-Fi. Problems galore. Sitting next to original Dual PowerMac G5, the Dual showed full signal the quad had intermittent connections. Fine for a week or so then a nightmare etc.

I ended up performing a clean install (erase and install) of the OS and the problem was fixed. Never had an issue from then on.

You could try an erase and install, see if that resolves the issue

I just bought a new 27" i5 iMac today, put it up next to my 24" iMac and got ready for transition. But yes, I have the exact same slow wifi problem with my new machine. I have a 20 mbit connection which I share through a Time Capsule. On my 24" iMac I get about 16 mbit, but on my new 27" iMac I only get about 6-8 mbit. WHY? I've tried to change channels, DNS, security settings, and a lot of other things. My MacBook Air also gets 16 mbit. Aaaargh. Frustration!!!!!

The last few weeks, I've been having the axact same problem, only I'm using 10.5.8 on a 20'' bought last january, so it's over a year old. There has never been a problem before, but I'm experiencing very much the same things as 27'' users are describing here and in other threads. As most other people, I've been through a lot of futile attempts of solving it, but it doesn't do any difference. And as most other people, there isn't a problem with the other computers connecting through the router (an Airport Express, there are 2 PC laptops that also use it).
This is really confusing me: shouldn't .11n stay way over 100mb/s? I'm staying between 0-40 Kb/s, then it suddenly rushes to 400 during a couple of seconds and then back to "normal" (awful, that is).

Exactly the same problem. Works fine for a while and suddenly disconnects from the network. No other wireless device is then visible (usually sees 3 to 4 nearby routers) and the only solution is to reboot to iMac... Here's the log info describing the crash, if it helps anyone:


10-03-16 5:27:25 PM kernel ----->>> ar5416GetPendingInterrupts[117]: received AR INTR_SYNC_RADM_CPLTIMEOUT interrupt SyncCAuse 10001000
10-03-16 5:27:25 PM kernel ---------->>>> ath_intr[2723] ------- FATAL ERROR ---- NEED RESET ----
10-03-16 5:27:25 PM kernel ---------->>>> ath_intr[2725] ------- FATAL ERROR ---- RESET DONE ----
10-03-16 5:27:25 PM kernel ----- ar5416Reset[192] ---- Unable to set powe mode ----
10-03-16 5:27:25 PM kernel ath_reset: unable to reset hardware; hal status 15617791
10-03-16 5:27:26 PM kernel ----- ar5416Reset[192] ---- Unable to set powe mode ----
10-03-16 5:27:26 PM kernel ath_reset: unable to reset hardware; hal status 15617826
10-03-16 5:27:27 PM kernel ----- ar5416Reset[192] ---- Unable to set powe mode ----
10-03-16 5:27:27 PM kernel ath_reset: unable to reset hardware; hal status 15617826
10-03-16 5:27:27 PM kernel ----->>> ar5416GetPendingInterrupts[92]: received PCI FATAL interrupt SyncCAuse 40c40420
10-03-16 5:27:27 PM kernel ----->>> ar5416GetPendingInterrupts[109]: received AR INTR_SYNC_RADM_CPL_TLPABORT interrupt SyncCAuse 40c40420
10-03-16 5:27:27 PM kernel ---------->>>> ath_intr[2723] ------- FATAL ERROR ---- NEED RESET ----
10-03-16 5:27:27 PM kernel ---------->>>> ath_intr[2725] ------- FATAL ERROR ---- RESET DONE ----
10-03-16 5:27:28 PM kernel ----- ar5416Reset[192] ---- Unable to set powe mode ----
10-03-16 5:27:28 PM kernel ath_reset: unable to reset hardware; hal status 15617826
10-03-16 5:27:28 PM kernel ----- ar5416Reset[192] ---- Unable to set powe mode ----
10-03-16 5:27:28 PM kernel ath_reset: unable to reset hardware; hal status 15617791
10-03-16 5:27:28 PM kernel ----- ar5416Reset[192] ---- Unable to set powe mode ----
10-03-16 5:27:28 PM kernel ath chanset: unable to reset channel 1 (2412Mhz) flags 0xc0 hal status 1467764736 : Attemptying HailMary Reset
10-03-16 5:27:29 PM kernel ----- ar5416Reset[192] ---- Unable to set powe mode ----
10-03-16 5:27:29 PM kernel ath chanset: unable to reset channel 1 (2412Mhz) flags 0xc0 hal status 1467764736 : HailMary Failed !!
10-03-16 5:27:29 PM kernel ----- ar5416Reset[192] ---- Unable to set powe mode ----
10-03-16 5:27:29 PM kernel ath chanset: unable to reset channel 6 (2437Mhz) flags 0xc0 hal status 1462 : Attemptying HailMary Reset
10-03-16 5:27:29 PM kernel ----- ar5416Reset[192] ---- Unable to set powe mode ----
10-03-16 5:27:29 PM kernel ath chanset: unable to reset channel 6 (2437Mhz) flags 0xc0 hal status 1462 : HailMary Failed !!
10-03-16 5:27:30 PM kernel ----- ar5416Reset[192] ---- Unable to set powe mode ----
10-03-16 5:27:30 PM kernel ath chanset: unable to reset channel 11 (2462Mhz) flags 0xc0 hal status 1462 : Attemptying HailMary Reset
10-03-16 5:27:30 PM kernel ----- ar5416Reset[192] ---- Unable to set powe mode ----
10-03-16 5:27:30 PM kernel ath chanset: unable to reset channel 11 (2462Mhz) flags 0xc0 hal status 1462 : HailMary Failed !!

I thought I might add the settings that I use, if it helps anyone in locating the problem. I've checked the statistics for the router, and the signal/noise ratio for my connection is excellent (-70/-90) as far as I can tell.

I'm using an airport express (Version 7.4.2) as a router. It's located about 5-7 meters from my iMac. The wireless mode is set to "Create wireless network", the security is set to WPA/WPA2 Personal (I've tried WEP and WPA2 as well, without improvement). The channel is set to 11 (I've tried 1, 3, 6, 9 and 13). The radio mode is set to 802.11n (802.11b/g-compatible). I'm connecting to my modem by ethernet . I'm setting IPv4 by DHCP. The setting for Ethernet WAN-gate is set to Automatic, and the connection sharing is set to Off (bridgemode).

For the iMac, I'm configuring IPv4 by DHCP, and IPv6 automatically (I've turned IPv6 off on the Airport Express, however, so I'm not actually using IPv6 and haven't recieved any adress). I'm not using any proxy, however I am using passive FTP-mode (PASV).

I'm not sure if posting statistics would be helpful to anybody? I could obviously do that...

I've had the same problem. I think that reciever of the airport card in the new imac isn't that strong. In fact, close to the wireless router I have a good connection speed. From a greater distance of the router the speed is decreasing rapidly (obvious ? Well, this is not the case on my pc laptop). I've solved it by using a wireless extender PLC.

Any fixes for this yet? Im having the same problem as described by everyone in this thread

I actually managed to solve my problem, which was the firewall in the modem, that seems to have conflicted with the Airport Express for some reason. I don't know if this is the same problem that others have had but it might at least be worth trying?

My 27" iMac connects sporadically. My macbook sitting next to it connects with no problem. I emailed Apple and told them of the problem. They're supposed to call me back tomorrow.

I think it's the metal case is the problem. My powerbook never got good wireless reception either.

I did what another user said to do and changed to Airport the first in the list in network preferences. It seemed to work a couple days and then stopped working again. Very frustrating.

Apple called as requested. He had me go to Finder/hard drive/library/preferences/system configuration and delete the folder and restart. It's been working pretty well since. However, it's worked for a couple days in the past and then stopped again. Time will tell.