Flaky imac to timecapsule wifi but printer OK

Question

We have a new (purchased Sept 22) iMac and time capsule. The wifi connection
between the iMac and the TC (which is our router as well connected to a cable
modem) is flaky. A Linux machine connected to the TC by ethernet always connects
to the internet just fine, and can print to a wifi printer via the TC just fine,
but often the iMac seems to "connect" to the TC, but nothing really happens --
mail times out, browsers time out or run extremely slowly. Sometimes this can be
fixed by turning airport off on the iMac and then back on. Today it was really
bad, and Airport Utility couldn't even find any wireless devices, even with
reboots of the iMac and the TC. So I connected an ethernet cable for the iMac,
even though I prefer the wifi, and suddenly both connections are up (ethernet
and wifi). This is extremely frustrating. Any help will be greatly appreciated.
I did find something funny in the Time Capsule log of this mornings weirdness:
there were two 'associateds' for the iMac, and then a constant series of
attempts to associate that were deauthenticated after a couple of seconds:
Oct 30 10:02:33 Severity:5 Initialized (firmware 7.3.2).
Oct 30 10:02:35 Severity:5 (WAN) link state is Up.
Oct 30 10:02:35 Severity:3 No Address for NTP server time.apple.com.
Oct 30 10:02:35 Severity:5 Deauthenticating with station ff:ff:ff:ff:ff:ff (reserved 3).
Oct 30 10:02:35 Severity:5 Rotated TKIP group key.
Oct 30 10:02:39 Severity:5 Internet Configuration leased -- host <75.118.6.202/255.255.252.0> gateway <75.118.4.1> dns <64.233.222.2 64.233.222.7> wins lease <604800> domain <wowway.com>
Oct 30 10:02:46 Severity:5 Associated with station 00:21:e9:e4:a5:5c
Oct 30 10:02:47 Severity:5 Associated with station 00:21:e9:e4:a5:5c
Oct 30 10:02:48 Severity:5 Deauthenticating with station 00:21:e9:e4:a5:5c (reserved 2).
Oct 30 10:02:48 Severity:5 Disassociated with station 00:21:e9:e4:a5:5c
Oct 30 10:02:51 Severity:5 Clock synchronized to network time server time.apple.com (adjusted +4 seconds).
Oct 30 10:02:57 Severity:5 Associated with station 00:21:e9:e4:a5:5c
Oct 30 10:03:01 Severity:5 Deauthenticating with station 00:21:e9:e4:a5:5c (reserved 2).
Oct 30 10:03:01 Severity:5 Disassociated with station 00:21:e9:e4:a5:5c
Oct 30 10:03:12 Severity:5 Associated with station 00:21:e9:e4:a5:5c
Oct 30 10:03:15 Severity:5 Deauthenticating with station 00:21:e9:e4:a5:5c (reserved 2).
Oct 30 10:03:15 Severity:5 Disassociated with station 00:21:e9:e4:a5:5c
Oct 30 10:03:19 Severity:5 Associated with station 00:21:e9:e4:a5:5c
Oct 30 10:03:22 Severity:5 Deauthenticating with station 00:21:e9:e4:a5:5c (reserved 2).
Oct 30 10:03:22 Severity:5 Disassociated with station 00:21:e9:e4:a5:5c
Oct 30 10:03:26 Severity:5 Associated with station 00:21:e9:e4:a5:5c
Oct 30 10:03:29 Severity:5 Deauthenticating with station 00:21:e9:e4:a5:5c (reserved 2).
Oct 30 10:03:29 Severity:5 Disassociated with station 00:21:e9:e4:a5:5c
Oct 30 10:03:34 Severity:5 Associated with station 00:21:e9:e4:a5:5c
Oct 30 10:03:37 Severity:5 Deauthenticating with station 00:21:e9:e4:a5:5c (reserved 2).

Answer 1

b3nbranch,
Welcome to the Apple Discussions!
*_Time Capsule Weak Signal Strength / Dropped Connections_*
Forgive the size of the post, but the suggestions below have helped others with similar issues. Try each topic individually and see if things improve, If not move on to the next one.
*Keep the Time Capsule Cool*
Some posters have observed that when they positioned the Time Capsule for better ventilation and cooling, their network connectivity issues resolved themselves. Also avoid locating the devise within poorly ventilated cabinets or piling items around or on top of it.
*Time Capsule Orientation*
While the location you chose to setup your Time Capsule may be acceptable, but the direction it is oriented can have an effect on signal strength. It appears that the signal of the Time Capsule does not radiate equally from all sides of the devise.
The antennas within the devise are positioned along the 3 smooth sides. That is, there is no antenna on the side bearing the ports and cables. As a result, position the devise with the ports and cables AWAY from the direction of most of the clients that will be connecting to it.
*Cordless Phones*
Some users have discovered that the cordless phones they have in the home occupy or are near the same bandwidth as their wireless network (2.4Ghz or 5Ghz). Try temporarily disabling the handsets and their bases and see if network connectivity improves. If so you may need to change the channel that the phone uses or purchase phones that occupy a different bandwidth.
*Proximity To Other Devices*
One poster observed: “Finally have full access, full speed, and full functionality. Initially I installed the Time Capsule at the location of my cable, cable modem... which of course was next to my HDTV, DVD, Apple TV, Amplifier, etc. Get the picture? After about 4 weeks of starts and stops, resets and repeated initial backups, I moved the unit to another location, closer to my Mac, and in an area where there are no other electronics. Now, it runs perfect.” [http://discussions.apple.com/thread.jspa?threadID=1734818&tstart=0]
*Change Firewall Settings* #
Go to System Preferences --> Security.
Click the Firewall tab.
Change setting to “Set access for specific services and applications”.
The System will now ask you when each process wants to penetrate the firewall. Once you click “Allow” each time you are asked, it will be saved in the pane at the bottom of this window and it should never ask you again.
One poster observed, “Since I made this change, my wireless has been strong and Time Machine works like a champ and the impact on my network performance is minimal. I speculate that the change in performance is due to security protocols or services that run in the 'allow all incoming connections' and 'allow only essential services' modes. Whatever the reason this fix has worked for me for over 2 months without resetting my airport connection or time capsule.” [http://discussions.apple.com/thread.jspa?messageID=8348496#8348496]
*Change Time Capsules’ Channel*
Launch Airport Utility.
Select the device on the left.
Click "Manual Setup."
Select “Airport” in the toolbar.
Click the "Wireless" tab.
If “Channel” is set to “Automatic” try changing to a different one. Holding the Option key down and clicking the drop-down menu should provide more channels to choose from. If you have another wireless router operating, ensure that each devices’ channels are as far apart as possible.
Click “Update”.
Close Airport Utility.
*Preferred Networks & Airport Services*
You may be experiencing interference from other networks in your neighborhood. When you click the Airport menu are there other networks listed other than your own?
If so, is your network at the top of the list? It should be.
Go to System Preferences --> Network --> Select Airport on the left.
Click "Advanced". In the “Airport” tab note the various local wireless networks that Airport detects. Is the network you prefer to connect to at the top of the list? If not drag it to the top. Are there other networks you never intend to connect to (an old work network, or a neighbors network)? Then highlight them and click the "-" button.
Make sure “Remember any network this computer has joined” is checked.
Click "OK".
For "Network Name" be sure your network is selected and then click "Apply".
Is Airport (wireless) your primary means of connecting to your network? If so, is Airport at the top of the list of services on the left? It should be.
Click the small “Gear” button at the bottom of the window and select “Set Service Order”.
Now drag Airport to the top of the list.
Click “OK”. Click “Apply”.
Now see if network connectivity has improved.
*Transmit Power & Wide Channels*
If you are using the 802.11n only (5GHz) radio mode, you can also select to use wide channels, which provide higher data throughput in your network.
Launch Airport Utility
Select your Time Capsule on the left.
Click “Manual Setup”.
Select “Airport” in the toolbar.
Click the “Wireless” tab.
Click “Wireless Options...” at the bottom of the window.
Adjust the “Transmit Power” to 100%.
Put a check mark in the box labeled “Use Wide Channels”. (If you are using a 802.11a/b/g (2.4GHz) radio mode then select “Interference Robustness”)
Click “Done”.
Click “Update” in the lower right hand corner.
Wait for the Time Capsule to restart and then see if your network speeds improve.
Let us know if any of the above helped improve your situation.
Cheers!