I'm having some trouble understanding a login issue in my network setup, and I could really use some help. We have a sonicwall that manages our DHCP, with multiple subnets configured. Our internal wireless devices are on the 172.16.x.x subnet, while the LAN traffic operates on the 192.168.x.x subnet. Devices can communicate across these subnets without any problems.
We've got a Windows domain server set up for our network, which is running fine as well. The issue arises with a specific domain computer (let's call it Computer W) and a user (User X) who has never logged into that computer before. When User X tries to log in while connected to the wireless network, they get a message saying the username or password is incorrect. I, as the admin, also haven't logged into Computer W previously, but I can log in without any issues, creating a local account in the process.
After this, I tried to log out, but User X still couldn't log in. However, I ran an Ethernet cable to Computer W, switching its connection to the 192 subnet. After connecting via cable, User X was able to log in successfully and create a local account. When I disconnected the Ethernet and reverted back to wireless, User X was able to log in over the 172 network without problems.
This situation is so weird, and I have no idea why I could log in while User X couldn't. I would appreciate any insights or thoughts on what might be going wrong!
5 Answers
It sounds like your admin credentials might have been cached somehow—maybe due to some previous setup or a remote admin tool. Check your traffic rules for Kerberos and LDAP ports. From Wi-Fi, see if you can discover your Domain Controller and if DNS lookups are functioning properly.
Remember that domain accounts and local accounts are distinct. Make sure you're trying to log in as the correct account type. If the computer is domain-joined, User X should be able to use their domain credentials.
When you logged in as admin over Wi-Fi, is it possible that the account you used exists as both a local and domain user? If you logged in with a local account due to the Domain Controller being unreachable, then switched to a wired connection to access the domain, that may explain the behavior. Try resetting the user's password in Active Directory and see if they can log in over Wi-Fi with their old password to check if cached credentials are in play.
Try pinging the Domain Controller's IP address while using the Wi-Fi connection. Also, see if you can ping it by hostname to check connectivity.
First things first, double-check that both of your subnets are using the same DNS settings. Also, ensure that the wireless VLAN isn't blocking any Domain Controller traffic, like Kerberos or LDAP. Sometimes, a device might even mark Wi-Fi as an untrusted network, which can create login issues.
Don't forget that if it's domain-joined, you should only have the domain DNS set up, just to be safe!