Macbookpro internet slow / site not found but only Mac on LAN with problem

Question

I replaced my MacBookPro in Aug10, it is up to date with latest software, etc. It generally does OK even if it's not as fast as I expected generally, but I regularly have internet problems. Problem is either very slow connection, or at times it will come up with "Safari can't find the server" while my old Mac G5 right next to it on the same LAN, same router, same DNS etc connects to the site no problem. Also our iMac upstairs on the same (wired) LAN does not have the same problem. All machines have Firewall on. The MBP will also sometimes fail online backup to me.com which also indicates a connectivity problem.
any suggestions where to start looking?

Answer 1

First of all what router are you using? There have been some known issues circulating about this. So your router manufacturer will be important.
So what I understood is you are having issues with wired and wireless connections? And that the cat5 cable is a known good cable? If your computer can support a gigabit connection as wel as your router try using a cat6 cable. But that will be irrelevant to the issue.
The big question is how far away are you from the router - distance = enemy. If you are running a 100 foot long cable that's your issue right there.
First troubleshooting step:
-Create a new administrator user and call it test
-log out of current user and log into the TEST account
-see if you can connect to the internet
-if you can connect to the internet your main user account is corrupt, backup your data, delete that user acount, recreate it
If not try all of the stuff below:
Other than that try these trouble shooting steps:
-Power cycle you modem and your wireless router
-Go to into system preferences > network > click on ethernet > click advanced > click on TCP/IP
-Where it says IPv6 select that drop down box and choose the"off" selection to turn ipv6 off
-Where it says configure ipv4 make sure that it says "Using DHCP"
-If it says that hit the "Renew DHCP Lease button"
-Go to the proxies tab and make sure none of the proxies are selected
-Click on the ethernet tab and make sure next to Configure it says "automatically"
For the Aiport selection:
Do the same thing above
After testing and verifying those settings shutdown your computer:
-Once shut down reset System Management Controller
->With machine powered down pull the battery out if it is a removeable batter, then unplug the AC adapter
->Hold down the power button for ten seconds
*! If you cannot remove the batter unplug the AC Adapter and hold down left shift key + control + option + hold down the power button for 10 seconds
After resetting the SMC we will reset PRAM next:
-with the machine powered off hold down:
-option + command + R + P
-Hit the power button and release and make sure you are holding all four of those keys while the computer boots up
-You will hear the initial chime, boot to a white screen, then restart to a black screen and you will hear a second chime... release all the buttons and let it retsrat into the OS
Once back inside the OS go back into System Preferences > Network > click on Airport:
If you wireless network is in the Preferred Networks or is showing up in the Network Name on the first preference window then we know your wireless airport hardwars is functioning properly
If none of that fixes the issue you can try pulling these files:
Macintosh HD/Library/cashes/ -> select and delete all those files inside of that folder
~(~means home folder)/Library/Preferences/com.apple.systempreferences.plist
~/library/preferences/com.apple.internetconfig.plist
~/library/internet plug-ins/ ->make sure that folder is empty if not delete any plugins
Open up Safari:
Click on Safari menu option > Reset Safari > Check Eveyrthing > Reset
Click on Safari menu option > Empty Cache > empty
Now if you cannot get an internet connection after all that.... try this:
-mac hd/applications/utilities/run disk utility
-select on volume macintosh HD and on the window to the right click on verify disk
-if disk needs to be repaired go to the next trouble shooting step if not go to the next section
-if it needs to be repaired, insert the OS X installation dvd 1
-shut down the computer, hold the C key down and power on the machine
-hold the C key until you get the white screen with the apple and the spinning gear and you hear the dvd spinning
-takes a bit to load, the next screen is select your language then hit the next arrow
-when everything loads up there will be a menu option called utilities on top of the screen, select that
-in that menu select disk utility, click on Macintosh HD, then click on repair disk (most likely you won't need to do this for a wireless issue but I am giving you every troube shooting step possible)
If the volume appeared to be ok, load back into the OS:
Most likely it is an issue with your router even if other devices are connecting to the router
-go to your routers website and download the latest firmware upgrade for your router
-or you can login to the router and update firmware through that, i know linksys uses 192.168.1.1 or something like that
If a firmware update doesn't work we can go ahead and assign your computer a static IP address:
(for both airport and ethernet connection)
-Go to system pref > network > click on airport > click advanced > tcp/ip tab
-Where it says configure IPv4 write down the IP address it has there, so for example lets say it says 192.168.1.10
-Click the dropdown next to configure IPv4 and select "Using DHCP with Manual Address"
-erase all the 0's and type in 192.168.1.180 (notice this is just an example IP address use the one your router gives you)
With a static IP address we only change the the last digit if we are using the routers DHCP otherwise we will have to go in and configure the router.
Do the same thing with the Ethernet connection but make sure the last digit is like 190 and not 189
Sometimes when you have a lot of devices on the network there could be conflicts with the IP addresses and typically consumer grade routers it will assign IP addresses 1-10 for the last digit so if we use a higher number it will be less likely to have a conflict.
Now if THIS doesn't resolve the issue we have other options:
Reset the Router to default factory settings, remove the password from it
Make sure the router is broadcasting in "N" not all of b, g, and N. If all yoir devices can read the N wireless signals have your router broadcast in just N!
If that doesn't work, put in your Mac OS X Install dvd 1 and do an archive OS install (you wont lose data or applications)
Once that completes and it still doesn't work, back up your data, boot into the install DVD, open up disk utility, click on the top most HD option not macintosh HD
-click on the erase tab
-erase the hd, make sure mac os journaled is the selcted format and make sure the name says Macintosh HD
-once erased close ut of disk utility and continue with the installation from the booted installation disk
IF that does not resolve the issue contact your ISP
Make sure you have the latest firmware for you router
Go out and buy an airport extreme
Most likely it will be some setting inside of the router
You may have your router to accept only MAC addresses and you never added your new computers mac address to the list so it won't be accepted by the router
If none of those troubleshooting steps don't help your pretty much SOL, go out buy a new router and new ethernet cable.