MacFixIt Answers

MacFixIt Answers is a feature in which we answer questions e-mailed from our readers. This week we have questions on Wi-Fi routers crashing when a specific Mac connects, Web pages not fully loading in Safari and Firefox, and using a computer firewall in addition to a network firewall. We continually answer e-mail questions, and though we present a few here, we certainly welcome alternative approaches and views from readers and encourage you to post your suggestions in the comments.

Question: Wi-Fi router crashing when Mac connects

MacFixIt reader "Tim" asks:

I have bought a brand-new MacBook Pro with i7. Everytime I use the AirPort to connect to my Wi-Fi at home, which is an ADSL (connected to phone line), it crashes the modem, causes the DSL button to flash red, and the computer loses the connection. The same problem occurs every time I wake the computer from sleep mode. It does not occur with an Ethernet cable connected. I have updated the firmware for the modem, emptied every cache under the sun, updated all software, but no dice. The MacBook works fine at work, which has a WPA2 connection--mine at home is WPA.... Apple, in its infinite wisdom, claims it's not an issue with their software but with the modem.

Answer:

This could be anybody's fault, and naturally each company will blame the other, leaving you stuck in the middle with no answers. Unfortunately, it will likely be tough to root out the problem; however, it is likely that you can do it by trying different router settings. First check any hardware settings such as broadcast channels and range, along with any others that your router supports. In addition, try changing your authentication settings (i.e., to WPA2 from WPA, or vice versa) to see if that routine in the router is causing the crash. Finally, try disabling any extra features, such as dynamic DNS (if you use that), UPnP, or any extra broadcasting or firewall features that the router has.

While these features may and should work with other PCs, there could be a small incompatibility with your Mac in any of them.

On the Mac side, there is not much you can configure with the wireless card; however, you can try removing some settings and configurations to see if you can clear the problem. Go to the "Network" system preferences, select AirPort, and click "advanced." In the AirPort tab remove all preferred networks, and in the 802.1X section remove all user profiles and authentication information. Lastly, go to the Ethernet section and set it to be configured automatically (though you can manually set different MTU sizes--try 1492 or 1500).

Question: Pages not fully loading in Safari and Firefox

I have the latest OSX, newest version of Firefox and Safari, with all add-ons etc. updated. I have rebooted, restarted the browser, created a new profile, but the pages on some sites, Ebay, Amazon, etc. are not loading, all we get is text. Images and banners do not load; rather, an empty box appears almost as if the page didn't finish loading completely.

Answer:

This is likely a DNS-related issue, or one where the router is denying traffic from various Web locations. Try bypassing the router altogether by plugging your computer directly into your modem. This will prevent the router's firewall and NAT features from interfering with traffic coming directly from your ISP. In addition, if you have any custom DNS settings in your Network system preferences, then try removing them to see if that clears the problem. Conversely, you can try adding some public DNS servers to see if that helps resolve the problem. Some options are Google's Public DNS servers (8.8.8.8, 8.8.4.4) and the OpenDNS servers (208.67.222.222, 208.67.220.220).

Question: Using a computer firewall in addition to a network firewall

I have the firewall in my iMac running. I am also running Norton AntiVirus with Vulnerability Protection, which recently has been blocking several Portscans and MS SQL Stack BO attacks that apparently originate in China.

I plan to set up an AirPort wireless network. I read that AirPort will have its own firewall.

Will the AirPort firewall be sufficient? Will there be any conflict if I run both the AirPort and iMac firewalls? I assume that whichever firewall is running, I should keep Norton AntiVirus running.

Answer:

The AirPort base station will have a fairly robust firewall that will work to block most malicious activity. While you can also have a software firewall enabled, some applications may have difficulty working through multiple firewalls (this is a rarity though). If you are concerned about attacks, you can always start by enabling both firewalls, and then troubleshoot specific problems if they occur. A network firewall will only protect the private network from attacks, whereas a system or software firewall will protect the computer from attacks that originate from the local network in addition to those that come from the Internet.

Having a virus scanner available will also help (though the number of Mac-specific threats is relatively very small in comparison to Windows). The amount of Mac malware will grow, though there is debate about how fast and how much of a threat it will be, and so on. Ultimately it's tough to properly characterize the exact nature of cyberthreats for the Mac, but to be safe you can always keep the scanner updated and run it regularly. I currently would not keep the scanner set to on-access scanning, or have it monitor all files continually; however, I would set it to regularly (weekly/monthly) scan work folders like the Downloads folder or the Desktop.

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