Question Small business – LAN is OK, internet is not. But not for everyone, and not all the time

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mgrammas

Jun 15, 2020
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A slowly growing number (but still not all) of users have problems getting an internet connection when they fire up their devices on our network. With one exception, they are all laptops. Everybody can access local file and app servers. It’s just internet access that’s the problem.

I’ve noticed that devices like desktops that are up and running 24/7, have no problems.

It’s not just a first thing in the morning problem, either. If someone walks into the office at 3:00 pm and turns on a laptop, they may have this issue.

It’s both Wi-Fi and ethernet connections, but ethernet seems more problematic.

Sometimes disabling and enabling the ethernet card works. Sometimes rebooting once or twice works. But mostly just waiting anywhere from 5-30 minutes works.

It isn’t everyone (but everyone seems to get his/her turn), and it’s not always – my favorite kind of problem.

I would appreciate any suggestions, and will provide as much further information that is requested.


Thank you for your help!

Mike Grammas
 
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How many devices on the network (wired and wireless)?

Are the laptops being taken home or otherwise being connected to other networks?

What router is being used? Are you able to log into the router's admin page to view a list of connected devices?

What range of DHCP IP addresses is available? Any limits set on the number of allowed connected devices?

Any network devices with static IP addresses? Are those static IP addresses outside of the established DHCP IP address range and reserved for a given device via the device's MAC?
 
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While there might be lots of reasons for that,
I would imagine the DHCP is running out of free addresses to hand out.
To solve it, you can either shorten the lease or widen the network.
Try changing the LAN netmask from the usual 24bit to say 22bit (255.255.252.0 instead of 255.255.255.0) and see what that does.
 
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Ralston18 said:
How many devices on the network (wired and wireless)? About 115

Are the laptops being taken home or otherwise being connected to other networks? Yes.

What router is being used? Are you able to log into the router's admin page to view a list of connected devices? It is a soon to be replaced WatchGuard T50, and I do have admin access.

What range of DHCP IP addresses is available? Any limits set on the number of allowed connected devices? The DHCP addresses begin at .100. I don't know about any limits (or how to look it up).

Any network devices with static IP addresses? Are those static IP addresses outside of the established DHCP IP address range and reserved for a given device via the device's MAC? Desktops and printer have static IP addresses, and they are all below .100.
Click to expand...

I feel like you might suggest that we're running out of DHCP addresses. I ran into the same "no internet" problem when I was the only one in the office last night.
 
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kanewolf said:
With 115 devices, what is the allowable range of DHCP IDs? 192.168.0.101 through 0.140
Is network hardware, printers and other static IP devices in that same subnet? Network hardware and anything static is below 0.101

DHCP "starvation" would be my first guess also.
Click to expand...

The DHCP leases are for eight hours, so in theory, all of the laptops and smart devices should have given their addresses back overnight, right?
 
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Sorry, vov4ik_il, that should have read 0.101 through 0.240.

Why can't I insert a .jpg from my hard drive?

IP address 192.168.0.1/24
Lease time 8 hours
Start IP - 192.168.0.101
End IP 192.168.2.240
Reserved addresses - None
DHCP options - None
Default Gateway - use the interface IP address
 
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mgrammas said:
Sorry, vov4ik_il, that should have read 0.101 through 0.240.

Why can't I insert a .jpg from my hard drive?

IP address 192.168.0.1/24
Lease time 8 hours
Start IP - 192.168.0.101
End IP 192.168.2.240
Reserved addresses - None
DHCP options - None
Default Gateway - use the interface IP address
Click to expand...
Do you have "guest" WIFI? Is that in a separate subnet ? That can drive up your count quickly.
 
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I already see an issue:
Every device starting from 192.168.0.255 and all the way to 192.168.2.240 will be outside of your subnet. Valid hosts within this 24bit subnet are 192.168.0.1~192.168.0.254 with the first being the router interface. Fix the ending address as 192.168.0.254 for starters and see if that helps.
In case that does not help, change the netmask to 255.255.252.0 and change end address to 192.168.3.254. That will bump your host address space to 1022.
 
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vov4ik_il said:
I already see an issue:
Every device starting from 192.168.0.255 and all the way to 192.168.2.240 will be outside of your subnet. Valid hosts within this 24bit subnet are 192.168.0.1~192.168.0.254 with the first being the router interface. Fix the ending address as 192.168.0.254 for starters and see if that helps.
Click to expand...
They are outside the DHCP range, but that is OK. They are still in a /24 subnet. The DHCP address range doesn't have to go to 254. Mine stops at 199 for example.
 
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vov4ik_il said:
They are not. Unless it is a typo, 192.168.0.0, 192.168.1.0 and 192.168.2.0 are 3 different 24bit subnets.
Click to expand...
You are right. I missed the 2.240 in the second post. That wouldn't be a /24 either. It would have to be a /22

@mgrammas Can you verify the start and end IP address in your DHCP range. Are they ALL 192.168.0.x or does your DHCP range really go to 192.168.2.240 ?
If so your subnet mask is wrong.
 
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kanewolf said:
That wouldn't be a /24 either. It would have to be a /22
Click to expand...
Now we are on the same page, that is what I suggested earlier:
vov4ik_il said:
Fix the ending address as 192.168.0.254 for starters and see if that helps.
In case that does not help, change the netmask to 255.255.252.0 and change end address to 192.168.3.254. That will bump your host address space to 1022.
Click to expand...
Switching to 22bit will require changing the netmask on all fixed IP devices manually.
 
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I'm sorry guys, the end address is 0.240. We already use 192.168.1.xxx, 192.168.2.xxx, 192.168.3.xxx and 192.168.4.xxx for our four remote sites.

We recently set up a guest network for the home office (where the problem is - 192.168.0.xxx). I sent out an email this afternoon requesting that all smart phones and watches be moved to it ASAP.
 
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mgrammas said:
I'm sorry guys, the end address is 0.240. We already use 192.168.1.xxx, 192.168.2.xxx, 192.168.3.xxx and 192.168.4.xxx for our four remote sites.

We recently set up a guest network for the home office (where the problem is - 192.168.0.xxx). I sent out an email this afternoon requesting that all smart phones and watches be moved to it ASAP.
Click to expand...
Well, is there anything that prevents you from moving 192.168.0.0/24 to 192.168.10.0/22 ? And why the first 99 addresses excluded from the dynamic range?
 
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The first 99 are reserved for static IPs for servers, WAPs, desktops and printers.

I guess we could migrate to 192.168.10.x, but that could cause some headaches with file and app servers.

I don't understand how users can have this problem first thing in the morning, when DHCP leases from the day before have expired. Today's action from when I got into the office:
  • 50 DHCP addresses are in use
  • No internet on my laptop after powering up
  • Deleted the ethernet card in Device Manager, then did a rescan to reinstall it. That didn’t work. (Sometimes it does)
  • Disabled and enabled the ethernet card. That didn’t work. (Sometimes it does)
  • Disabled the ethernet card again.
  • Had to disconnect from the wireless network, then reconnect. Now I have internet.
  • Enable the ethernet card. Lost internet.
  • Four minutes later, I have internet.
  • Total time (today) – 6 minutes.
  • 56 DHCP addresses are in use

I want to see if getting people to move their phones/watches to the guest network makes a difference. We also have a new, way more robust router on order.
 
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What adddress did you get from DHCP if any?
You can only move the clients to the new segment and route servers to the new segment, should not bee too hard.
There is one more thing that can cause this - the ARP is not working properly. DHCP might be flushed but switches will remember old bindings. Try to flush ARP tables on your switches and set-up ARP aging on your L2 hardware.
 
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