Macs lose WLAN connection every hour

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Level 1

1 points

Macs lose WLAN connection every hour

I have an Asus RT-N56U router connected wirelessly to 4 Macs: 3 running Snow Leopard, 1 running Mountain Lion (10.8.3). For nearly a year now, I've been persistent problems whereby none of the computers are able to see one another over the LAN. The problem happens once every hour, and the only thing that appears to fix it is clearing the DNS cache on each machine by issuing the sudo dscacheutil -flushcache command in Terminal. The fix is only temporary: once an hour is up, the DHCP lease expires, and I lose my LAN connection again. This leaves me unable to connect to shared folders using Bonjour, print to shared printers, or even ping each computer's LAN IP. I've tried everything, from a factory reset of my router to reinstalling each computer's OS and rebuilding network settings from scratch. I'm at the point now where I'm seriously considering throwing out a $130, 2-year-old router; I run a small business from home, and I just can't manage without filesharing.

MacBook Pro (17-inch Early 2008), OS X Mountain Lion (10.8.2), 2.6GHz C2D 6GB GeForce 8600MT 512MB

Posted on Apr 2, 2013 11:07 AM

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Answer 1

Apr 2, 2013 11:20 AM in response to TeamHCN

Have you tried to set a higher value to DHCP lease time or reserve an IP lease to certain MAC address so that those computers always get the same IP.

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Answer 2

TeamHCN Author

Level 1

1 points

Apr 2, 2013 7:37 PM in response to Alberto Ravasio

How do I change the TTL in OS X? It's set to 1 day on the router. Also, what do you mean about reversing IP addresses? I am already using MAC address filtering. All 4 computers have manually assigned IP addresses which correspond to their MAC addresses; the manually assigned IP's are outside the normal DHCP to prevent the same address being given out twice.

None of the computers have any trouble connecting to the Internet; the issue is limited to LAN. I have a dynamic external IP assigned by my modem, the internal LAN IP's are static. I've tried using the Wi-Fi Diagnostic Utility in Mountain Lion, and I notice that, under the Bonjour tab, none of the other computers on my network resolve to a .local address.

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Answer 3

Apr 3, 2013 2:43 AM in response to TeamHCN

TeamHCN wrote:

How do I change the TTL in OS X? It's set to 1 day on the router.

As far as I know you can't. It's DHCP server, the service in your router, that rules. The client side on the Mac, just obeys to the server.

Also, what do you mean about reversing IP addresses? I am already using MAC address filtering. All 4 computers have manually assigned IP addresses which correspond to their MAC addresses

If you set this on the router, that's what I meant.

I've tried using the Wi-Fi Diagnostic Utility in Mountain Lion, and I notice that, under the Bonjour tab, none of the other computers on my network resolve to a .local address.

If everything is set properly you should be able to see printers and computers on your LAN in a snap.

If you can give us more details about your LAN configuration, that may be usefull to better diagnose the problems.

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Answer 4

Barney-15E

Level 10

112,590 points

Apr 3, 2013 5:29 AM in response to TeamHCN

TeamHCN wrote:

How do I change the TTL in OS X? It's set to 1 day on the router. Also, what do you mean about reversing IP addresses? I am already using MAC address filtering. All 4 computers have manually assigned IP addresses which correspond to their MAC addresses; the manually assigned IP's are outside the normal DHCP to prevent the same address being given out twice.

None of the computers have any trouble connecting to the Internet; the issue is limited to LAN. I have a dynamic external IP assigned by my modem, the internal LAN IP's are static. I've tried using the Wi-Fi Diagnostic Utility in Mountain Lion, and I notice that, under the Bonjour tab, none of the other computers on my network resolve to a .local address.

Instead of manually configuring IP addresses, set the Router to give them specific IP addresses within the DHCP range based on MAC address. Unless you're using an Airport Extreme, I can't tell you how to set that up on your router.

I have found that Manually configuring the IP addresses makes it difficult to get DNS from the DHCP server. You have to configure each Mac to get the DSN directly instead of through the Router.

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Answer 5

TeamHCN Author

Level 1

1 points

Apr 3, 2013 5:41 PM in response to TeamHCN

I appear to have solved the issue, somewhat by chance. The issue was with the router. The lease time for the network (WPA2) key was set to 1 hour. I reset the expiry time to zero, which means the lease will never expire. I never changed this, it appears to have been modified as part of a firmware update. It still doesn't make sense as to why the default value was a problem, or why it only affected assignment of LAN IP addresses. Anyways, it appears to be fixed.

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Answer 6

Apr 4, 2013 12:35 AM in response to TeamHCN

TeamHCN wrote:

It still doesn't make sense as to why the default value was a problem, or why it only affected assignment of LAN IP addresses

The DHCP service running on your router allocates IP LAN addresses. It's there to do that kind of task.

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Answer 7

Jul 8, 2013 11:59 AM in response to TeamHCN

Hey. Is this fix still working for you? I'm hearing a lot of complaints from Apple users that the latest firmware is messing stuff up. Have you had any other issues?

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Answer 8

TeamHCN Author

Level 1

1 points

Sep 22, 2013 12:01 PM in response to akalinchuk

Do you mean the latest Asus firmware? I am now on 3.0.0.4.374_239, and yes, I am once again having similar problems to those documented in the first post of this thread. However I'm less convinced this time that the router is to blame. The WPA2 key lease time is still set to zero (unlimited) on the router. Also, unlike last time only 1 computer is affected, and the problems appear to have started after I updated to 10.8.5. And finally, the connectivity issues are only affecting AFP shares (i.e. Bonjour), LAN IP addresses still resolve as normal.

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Answer 9

ahoi

Level 1

0 points

Oct 30, 2013 6:05 AM in response to TeamHCN

Thank you TeamHCN, your WPA2 lease time fix did it for me, works like a charm since a couple of days now.

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