Mac OS X 10.4: DHCP Problems: AirPort networking dropouts, D-Link router problems, more

Solutions

Shortening the computer name Shortening the Computer Name (to less than 6 characters) in the Sharing pane of System Preferences can underlying DHCP issues that affect D-Link routers and some AirPort configurations.

MacFixIt reader Al Spiegleman writes:

"Wrote earlier about a DHCP issue with Tiger - Seemed to affect some machines and not others. After talking to Apple tech support at length the only thing that they could offer is to change the computers share name. I was a little skeptical at the time, but I actually did it on a desktop and a couple of powerbooks, and lo and behold - they started getting DHCP addresses again.

"The actual fix involves going into the sharing preference pane and changing the computers name to a single word (I have kept it less than 6 characters, but I have no idea what the limit is) and closing the pref pane. DHCP will start to work immediately - either hard-wire or wireless. Don't even have to reboot.

"Trying to analyze what has changed - it appears that Tiger issues the DHCP request with a host name, which Panther did not. Appears that most implementations of DHCP have a limit on the number of characters (or words - not sure which) in the host name. The real problem of course, is with computers that have been set up with a long computer name because when you set up your Mac, the default is simply your name as typed in your log on, with "'s computer" added at the end. My partner's powerbook share name was 'Bruce LeVasseur's Computer". Changed it to blpbg4, and it magically started working again. My powerbook's name was G3400, so of course it worked fine without a change. This was a really tough one to diagnose, as it affected some machines consistently, and some not at all.

"Not sure if this is an Apple problem, or a DHCP problem, or a DHCP implementation problem, but this seems to fix the issue across the board - WAPs - DSL modems - Routers - you name it. Solved at least 12 customers' problems today with this."

Entering DNS server addresses MacFixIt reader Nico Oberbanscheidt reports that entering valid DNS server addresses (which can be obtained from your ISP) in the TCP/IP section of the Network pane of System Preferences resolves similar issues where the name-shortening workaround does not work.

In Nico's case, a PowerBook upgraded to Mac OS X 10.4 was not able to access the Internet via a previously functional AirPort connection, also breaking access for other machines.

Nico writes:

"I talked to an Apple-Care tech and he immediately suggested to fill in dedicated DNS-Addresses into the field 'DNS-Server (optional)' of Network-Preference-Pane / Environment Name / Show Airport (or Ethernet or others) / TCP/IP of the OS 10.4 Powerbook. After I had filled in two DNS-Addresses (in this german case 194.77.8.1 and 194.25.2.129) and connected to the airport-network, both the powerbook and the iBook where able to regain normal internet-access."

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