DHCP and connection woes

Question

DHCP and connection woes

Hi there.

I have a MacMini, running on OS X Lion, set up as a server.

I struggle to understand the server set up, and had an IT guy set up the configuration for me.

It worked fine for about 18 months, but recently all my devices/client computers have had intermittent problems connecting to the Internet.

Maybe once a week or so, for several hours.

The server is set up to be the DHCP issuer and DHCP is disabled on the router.

The Router has various port forwarding set up.

The server has a wired Ethernet connection to the router.

When the client computers (MBPs, ipads, iphones) lose their Internet connections, they can still see the wireless network, but are unable to join.

The mac mini server usually is still able to access the Internet - and able to connect to the router admin panel.

The router confirms its connected to the Internet.

Rebooting the router and/or server still doesn't allow the client computers to connect to the wireless network.

Can I assume, from this, that it's an issue with DHCP?

I have server admin tools installed, and when this issue arises, there's a green light next to DHCP in the settings.

To be honest, I don't use the mac mini as a server - as the main reason for it initially was remote access to files, etc, but I now use cloud storage.

I have a static ip address from my ISP (again, to access files remotely).

I do have a hosted website, and the email addresses for that are directed to and picked up by the server exclusively, so I'm guessing that if I stopped using the mac mini as a server, I'd lose those mails, but they're more historical, and I keep them for the odd stray message that comes through.

Bizarrely, the connections will just come back randomly on their own, but usually after several hours, of their own accord.

95% of the time, the network runs fine, but for that 5% of the time, it's frustrating as I also work from home, so it's a pain.

Can anyone advise how to resolve this? Or at least she'd some light on why it might be happening?

As the router isn't the DHCP issuer, wiring the client computers directly into it still don't allow them to connect to the network.

I'm tempted to disable DHCP on the server and enable on the router, but too scared, in case I can't connect at all due to a wrong setting - and I'm sure it's more involved than simply clicking "disable" in server tools (file sharing, etc?).

I wish I'd never had it set up this way, as I feel that if the router was the DHCP issuer, it would all run fine,

As a side note, I moved house in July and this has all started since then, despite not changing any settings at all.

It's the randomness of it that frustrates me, and how it will just connect again hours later, of it's own accord.

Sorry for rambling and the lack of technical info/knowledge.

Can anyone help? Please.

Mac mini, OS X Server

Posted on Nov 23, 2012 12:44 AM

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Answer 1

Nov 23, 2012 1:28 AM in response to GrandmaSmithy

Sorry, just to add:

As is blatantly obvious, I have all but a Luddite knowledge of all things server and networking.

If anyone is kind enough, or able to help, would you be able to explain in terms that a small child might understand (would say 8 year old, but suspect that may be well above my level, as they're very savvy these days!).

I'm willing to learn, but don't have much knowledge or experience.

I know. A classic case of "All the gear and no idea". Sorry!

Basically, I just want to use the mac mini as a client computer (media streamer) on the main network, rather than having it control the network.

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Answer 2

iToaster

Level 3

739 points

Nov 23, 2012 3:20 AM in response to GrandmaSmithy

could be the dhcp scope is not large enough for the amount of devices you have

this can happen if you've brought additional devices that connect to the network and the dhcp scope was orinally setup to only handle your original number of devices

for example orgianly had 2 macbooks and macbook pro, dhcp scope set to cover 3 devices

ipad iphone purchased, you're now 2 ip addresses short if all devices are in use

conections coming back randomly could be because the dhcp server is expiring ip address and making them avaible again.

dhcp ip addresses are leased for x number of hours , if the device comes back on line during the lease time the ip address is retained. Once the device goes off line and the lease time expires the ip address asigned to the device is released for use, the dhcp server will asign the freed address to the next device that requests an ip address

dhcp scope can be easily expanded providing you don't have a large number of devices

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Answer 3

Nov 23, 2012 3:40 AM in response to GrandmaSmithy

It is probably not applicable but I used to find that the old round AirPort Extreme base statations would periodically lock up and produce these symptoms. The newer square AirPort Extreme base stations did not have this problem.

These days I would not expect many people to still be using the round ones.

If you have a separate WiFi basestation to your Internet router and you have not rebooted the WiFi basestation then it might be the culrprite so try rebooting it. You could also try when this problem occurs not rebooting the Internet router and seeing if any other Ethernet connected computers are able to access the Internet and therefore see whether it only affects WiFi devices.

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Answer 4

Nov 23, 2012 6:38 AM in response to GrandmaSmithy

Thanks guys.

When the DHCP was set-up, we allowed for up to 25 clients, to cover all devices, printers, etc.

The loss of connection can also happen mid-connection, not just after the device has been in sleep/power off mode.

I don't have a separate wifi base station - and my MBP can't connect on a wired connection to the router either.

I would prefer to set up the router to handle the DHCP instead of the server.

Is this as simple as enabling on the router and disabling on the server?

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Answer 5

Nov 23, 2012 6:48 AM in response to GrandmaSmithy

I would monitor your DHCP connections in Server Admin to firstly see if your address pool isn't being over subscribed.

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Answer 6

Nov 23, 2012 7:04 AM in response to GrandmaSmithy

Unless you need to define custom DHCP option codes then yes you could switch to using the router for the DHCP server function.

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