DNS/DHCP Issue
I have a very strange issue that I'me having trouble nailing down. We first saw this issue when we had staff come back from a trip and they weren't able to connect to any of our WiFi networks but it seemed that they were able to connect via wired network. Each Wifi SSID is a different VLAN and subnet to limit broadcast traffic. The private network is divided into several VLANs but users are able to access other private network VLANs if they know the address. Guest VLANs can't access anything but the default route out to the internet.
Our VLANs/Subnets are configured on our core switch and DNS/DCHP is setup on Server 2012 R2. The switches and our WiFi controller pass the DNS/DCHP info from the server.
The issue is that any computer that has been connected regularly (on a daily basis) is still able to connect to the network(s) that it has been connected to. Any computers that have not been connected in a while, are unable to access the network. The other twist, they are able to access the wired VLAN via an ethernet connection, but can't connect to any of our wireless VLANs via 802.11g/n. I also untagged a port on the VLAN that we use for staff wifi and plugged a laptop into that port and I am unable to get an IP address, but untag the same port on the VLAN we use for all wired connections and it's fine. I've looked at the DNS and DHCP settings and examined the DHCP scopes to make sure the default gateway and DNS are properly configured on each one.
Unfortunately, I haven't made any head-way on this. I also uploaded a config from about a month ago to our core switch just in case it was a modification that had been made and things still wouldn't work, so I reverted to the config I have been running since the problem developed two - three days ago. I also made sure that all ports on all switches were tagged properly so that traffic could flow between devices.
Any help would be greatly appreciated.
Thanks, JJ
Our VLANs/Subnets are configured on our core switch and DNS/DCHP is setup on Server 2012 R2. The switches and our WiFi controller pass the DNS/DCHP info from the server.
The issue is that any computer that has been connected regularly (on a daily basis) is still able to connect to the network(s) that it has been connected to. Any computers that have not been connected in a while, are unable to access the network. The other twist, they are able to access the wired VLAN via an ethernet connection, but can't connect to any of our wireless VLANs via 802.11g/n. I also untagged a port on the VLAN that we use for staff wifi and plugged a laptop into that port and I am unable to get an IP address, but untag the same port on the VLAN we use for all wired connections and it's fine. I've looked at the DNS and DHCP settings and examined the DHCP scopes to make sure the default gateway and DNS are properly configured on each one.
Unfortunately, I haven't made any head-way on this. I also uploaded a config from about a month ago to our core switch just in case it was a modification that had been made and things still wouldn't work, so I reverted to the config I have been running since the problem developed two - three days ago. I also made sure that all ports on all switches were tagged properly so that traffic could flow between devices.
Any help would be greatly appreciated.
Thanks, JJ
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If they are able to connect to the WiFi again after connecting to ethernet (may have to be connected for a while), then I'd suggest the issue is some Group Policy change that happened while they were out, and that is required for the WiFi connection. But I'm not sure if that fits your scenario.
Hi There,
The issue is faced with your own staff which implies they are using company funded laptops.
Usually the settings of wiFi in an organization are pushed via group policies.Kindly confirm how the policies are pushed in your organization.
Also elaborate on the below:
I also untagged a port on the VLAN that we use for staff wifi and plugged a laptop into that port and I am unable to get an IP address, but untag the same port on the VLAN we use for all wired connections and it's fine.
The issue is faced with your own staff which implies they are using company funded laptops.
Usually the settings of wiFi in an organization are pushed via group policies.Kindly confirm how the policies are pushed in your organization.
Also elaborate on the below:
I also untagged a port on the VLAN that we use for staff wifi and plugged a laptop into that port and I am unable to get an IP address, but untag the same port on the VLAN we use for all wired connections and it's fine.
ASKER
Thanks for the advice. I did run out of IPs, so I had to reserve all addresses in each range as static, clearing any held IPs, and then releasing them.
I have seen this before. Try the following:
To Reset TCP/IP do the following from a wired connection
Delete all wireless profiles (NETSH WLAN DELETE PROFILE NAME="name")
Open cmd.exe with Run as Administrator
Then netsh int ip reset c:\resetlog.txt
Restart the computer
Remake wireless profiles as needed
Also, ipconfig /flushdns followed by net stop dnscache followed by net start dnscache
This will work in the majority of cases.