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[3000psi]

I have been researching this for literally months from the Mac side (Mac related forums, google) and have not been able to resolve it, so I thought I would give the smart folks here a try...

Problem:

I have a late 2008 model iMac and the DIR-655.  Using wireless, all network connections (local and to the Internet) are so slow that it is not usable.  The iMac connects fine and the signal strength looks good, but data transfer speeds are so slow that network applications and the browser are not usable.  Pings to the router are under 1ms until I fire up the browser, then pings time out.  Wireless on the same iMac in the same location running XP in bootcamp runs brilliantly, never a problem.  So obviously not a hardware issue.

Setup:  DIR-655 132NA with all default settings except for:

SSID set to my company name
Mode is mixed n and g
Channel Width: Auto 20/40
Security: WPA-Personal
WPA2 Only
AES

Environment: 4 wintel notebooks, 2 wintel desktops, 4 wifi enable phones, 2 wifi enable ipods all work fine on wireless anywhere in the house.  All cordless phones are 5gh or 900mhz.  The iMac is one of the closest machines to the router.  I am on several acres of land with no other access points in range.

What I have tried:

On iMac:

Deleting network plist files, keychain entries, and some other configuration files (all are rebuilt on reboot).
Manually configuring ip and dns entries in a new "location" .
Using public dns entries

On the router:

using different channels instead of auto
disabling security
n only mode
changing rts and fragmentation thresholds

Right now I have the iMac wired to a 1522 bridge so I can use it.  Bridge works fine.  Also, there have been times when the wireless works fine - usually after an OS upgrade.  One time it worked fine for 3 days.  But it always reverts back to unusable speeds at some point - usually in just minutes or seconds after I try some fix.

I would like to understand and solve this problem.  I think up to this point I have been trying a lot of other folks solutions to other problems (with similar symptoms).

So, how do I systematically diagnosis this problem and fix it (or determine that it is not fixable/out of my hands)?

Thanks in advance for any help.

SS

[NCTony]

What OS on the MAC?

[3000psi]

What OS on the MAC?

Sorry - should have provided that.  OSX, I believe I started with 10.5.6 and I have done every upgrade through the latest Snow Leopard.  After the 10.5.8 update, I had 3 days of working wireless, then it went south again.

SS

[NCTony]

So I would leave the RTS and Fragmentation settings at the defaults, the only difference I see on your setup from mine is I have my channel with locked at 20mhz. I don't have an imac but two macbook pro's, one on snow leopard 10.6.2, the other on leopard 10.5.8. Both work fine when they connect to my 655, although I normally use them on my 5ghz router.

Try changing the channel width setting to 20mhz only and see if it helps

[3000psi]

So I would leave the RTS and Fragmentation settings at the defaults, the only difference I see on your setup from mine is I have my channel with locked at 20mhz. I don't have an imac but two macbook pro's, one on snow leopard 10.6.2, the other on leopard 10.5.8. Both work fine when they connect to my 655, although I normally use them on my 5ghz router.

Try changing the channel width setting to 20mhz only and see if it helps

That is one that I have not tried - I will give it a shot when I get home later.

Are there any logs on either the Mac or Router side that would be helpful?

Thanks for your assistance!

SS

[NCTony]

Not that I am aware of but I think this may be the issue as I don't thing Apple supports wide channels in the 2.4ghz band. As a network professional I agree with this, wide channels in a band that only has 3 non overlapping channels is just asking for trouble.

Let me know what happens.

[3000psi]

Not that I am aware of but I think this may be the issue as I don't thing Apple supports wide channels in the 2.4ghz band. As a network professional I agree with this, wide channels in a band that only has 3 non overlapping channels is just asking for trouble.

Let me know what happens.

I was very hopeful as this is one option that I have not tried.  Anyway, changed the Channel Width to 20MHz, and just for good measure deleted all of the relevant plist files on the iMac and rebooted.  No improvement.  I appreciate the suggestion and I will keep plugging along.

With the bridge attached and working, this is not critical but I would like to understand and correct this.  My main motivation is that I would like to move from windows to mac as my main personal computing environment.  I have never been a big fan of Mr. Gates and in a formal life I was a Unix administrator so I am somewhat comfortable with the OSX philosophy/platform.  On the other hand I am practical and realize for better or worse most of the world revolves around wintel.  I won't buy a mac notebook until I get this solved.

Sorry if the philosophy got off-topic but as a mac user I thought you would understand.

SS

[NCTony]

Hmm...weird your settings are similar to mine, except I have the 1.21 firmware. I am wondering if the imac just doesn't like the dns relay? Seems odd, you could test it by disabling dns relay and rebooting the imac. I would also be interesting to see a nslookup to the same site, when you are connected to the bridge and then when you are connected wireless to the 655 direct. Basicly what I am wondering if the issue is just getting to the internet? And chance you have a NAS? Or can you setup one of the wintel machine with a network share you can see on the mac? If you can transfer data between two machines both on the AP fine but just can't get to the inet on the imac when connected to the 655 then it almost has to be a DNS issue. One more question, are you running the OS X firewall? If so turn it off just in case.

And I agree on the Mac, thats what both my home and work computers are mac's, wife and kids love it and daddy doesn't have to be tech support...As for my work macbook pro, I run XP in parallels for the few windows only apps I need.

[3000psi]

Hmm...weird your settings are similar to mine, except I have the 1.21 firmware. I am wondering if the imac just doesn't like the dns relay? Seems odd, you could test it by disabling dns relay and rebooting the imac. I would also be interesting to see a nslookup to the same site, when you are connected to the bridge and then when you are connected wireless to the 655 direct. Basicly what I am wondering if the issue is just getting to the internet? And chance you have a NAS? Or can you setup one of the wintel machine with a network share you can see on the mac? If you can transfer data between two machines both on the AP fine but just can't get to the inet on the imac when connected to the 655 then it almost has to be a DNS issue. One more question, are you running the OS X firewall? If so turn it off just in case.

And I agree on the Mac, thats what both my home and work computers are mac's, wife and kids love it and daddy doesn't have to be tech support...As for my work macbook pro, I run XP in parallels for the few windows only apps I need.

No NAS but I do keep most of my files on an HTPC connected to the 655 via ethernet.  I have a share on the HTPC which I access from the iMac.  Anyway, when I have the iMac on wireless (not bridge), the share is flaky - keeps disconnecting.  Any applications that use files on the HTPC (I keep my iTunes lib on the HTPC and run iTunes against that library from the iMac) do not work when on wireless.  Also pings to other computers on the LAN time out. 

When I first started researching this I also thought it may be DNS.  There are some write-ups about OSX using SRV vice DNS requests that some ISPs do not do well with.  When I noticed that lan connections and pings were not working, I gave the DNS issue less weight.  But it could still be related I suppose if resolving domains and or error messages from domain resolution is somehow keeping the router or iMac too busy to do other things.

A couple of questions on your suggestions:

Turn off DNS relay - I take it that you are referring to the setting on the router?  If I turn that off, do I need to specify ip addresses for the DNS servers somewhere?  Do I do that on the router or on the iMac (or both)?  I know there are places to do that on each, just need to know which one to pick.

Didn't even know about the Mac firewall.  I will look it up and turn it off if it is on.

BTW, there is a pretty good (as far as I can tell) analysis of the whole DNS/SRV thing on OSX here:

http://installingcats.com/tag/dns/

I had gone through most of his suggestions but was not able to improve anything.  Maybe I will give it another shot.

Thanks again.

SS

[lamonsas]

im using my imac and it works perfectly with the dir655 i got yesterday, whats ur hardware model?   

i ran a test on SPEETTEST.NET and it came up to 15.4mbp/s for download, thats awesome. i have time warner cable

[3000psi]

im using my imac and it works perfectly with the dir655 i got yesterday, whats ur hardware model?   

i ran a test on SPEETTEST.NET and it came up to 15.4mbp/s for download, thats awesome. i have time warner cable

Don't have the model number - it is a late 2008 24" iMac.  Anyway I know there are lots of folks who have macs that work great with the 655.  I am just not one of them.  There are also many folks like myself who have had fits with their wireless and my sense of it is that there is a constellation of possible causes.  I have pretty much eliminated hardware and interference.  In my case I am leaning towards an OS/Router/ISP compatiblility issue that needs some tweeking.

When on ethernet or wireless bridge I get 32 mbps download from the speedtest sites.  When on wireless it is less than 1mbps.

SS

ss

[lamonsas]

i ment what is the hardware model of your DIR655 , not your iMac.

[NCTony]

Ok well I doubt its a dns issue, we could be sure if you map the share on your mac to the HTPC via ip address and not by name (that may already be the case). And I use DNS relay, a setting on the 655, without any dns issues on my mac. How about a simple question, have you ever connected your imac to another wireless access point that didn't have any issues??

[3000psi]

Ok well I doubt its a dns issue, we could be sure if you map the share on your mac to the HTPC via ip address and not by name (that may already be the case). And I use DNS relay, a setting on the 655, without any dns issues on my mac. How about a simple question, have you ever connected your imac to another wireless access point that didn't have any issues??

Well, I thought I had tried another access point but I went ahead and gave it another try.  Turns out I have one of those little dlink pocket router/access points laying around (G730) so I hung it off the 655 and the imac connected fine (matched speeds with my wintel notebook).  I had the g730 set up with the same encryption - wpa2-personal.  Of course it is 802.11g.  So I knocked my 655 down to g only but that didn't work.  I then went ahead and backed up the 655 and reset to factory defaults.  Couldn't connect at all with the imac. 

So looks like I can connect to the g access point with no issues but just can't seem to get the 655 configured to work with the imac on osx.  Again, imac running xp in bootcamp works with the 655 brilliantly.

lamonsas, the hardware version on the 655 is A3.

What I really need here is a systematic way to debug the problem one layer at a time.  I just don't know how to do that.

Thanks again for the suggestions.  I guess it is a little bit of a consolation that I can connect to a g ap.  Maybe I will entertain a macbook on the next round of hardware upgrades.  I can always fall back to bootcamp in a pinch.

SS

[NCTony]

Very odd, so go back to a very basic config, chose a set channel 1,6 or 11, no security, make is visible, channel with set to 20mhz. Then shutdown all the other computers except the imac and see if it will connect and what happens. Just to be sure it's not fighting with another device for some reason