Avatar of HELFIT
HELFIT
Flag for United States of America asked on

Workstation loses internet

Have a couple of workstations that have a DHCP address and intermittently lose (only) internet connectivity. Their LAN connection remains stable. They can ping the gateway and the firewall, but are unable to ping an external IP address past the firewall. At first I thought it was DNS but they can't ping an external IP address. The outage lasts 2-8 minutes and then it's fine. I've tried searching for duplicate IP addresses on the LAN but don't see any. If I assign them a static IP address, outside the scope of DHCP it seems to resolve the issue. I can also ping their workstation from any other workstation on the network, however, NBTSTAT won't return a host for those affected users.
NetworkingDHCPDNS

Avatar of undefined
Last Comment
Benjamin Van Ditmars

8/22/2022 - Mon
SOLUTION
John

THIS SOLUTION ONLY AVAILABLE TO MEMBERS.
View this solution by signing up for a free trial.
Members can start a 7-Day free trial and enjoy unlimited access to the platform.
See Pricing Options
Start Free Trial
GET A PERSONALIZED SOLUTION
Ask your own question & get feedback from real experts
Find out why thousands trust the EE community with their toughest problems.
Wayne88

It won't be a DNS issue because he can't even ping out using IP address.

"At first I thought it was DNS but they can't ping an external IP address. "

Can they ping inside when they are unable to ping out?  It could be unstable network connectivity or bad cabling.  We have an issue with a network drop that's randomly inconsistent.

You may also want to do a traceroute to see how far they can ping and also pay attention to the hops and how long for each hop.  It should be fast when internal.
ASKER CERTIFIED SOLUTION
John

THIS SOLUTION ONLY AVAILABLE TO MEMBERS.
View this solution by signing up for a free trial.
Members can start a 7-Day free trial and enjoy unlimited access to the platform.
See Pricing Options
Start Free Trial
GET A PERSONALIZED SOLUTION
Ask your own question & get feedback from real experts
Find out why thousands trust the EE community with their toughest problems.
HELFIT

ASKER
I'll try resetting the TCP first. When it's happening, and I try a traceroute to an external IP, it doesn't even get to the first hop, the gateway, but I can ping the gateway, which is odd.
Wayne88

Sounds like the first hop is also the gateway/firewall.  You can ping it but it doesn't mean that it will allow traffic out from those two machines and when you give the machines a different IP address then it's fine.

Do you have a special firewall rule set specifically for the DHCP scope in question?
Experts Exchange is like having an extremely knowledgeable team sitting and waiting for your call. Couldn't do my job half as well as I do without it!
James Murphy
HELFIT

ASKER
The gateway and firewall are two separate devices. When this occurs, the tracert never reaches the gateway, but can ping it. I've had two of the workstations drop connection so did as John suggested and reset the TCP. We'll see if that sticks. I also will be trying to ping the workstation from the gateway if that happens again. This also happened again on a user that I gave a static IP to, so that's not a workaround.
John

Let us know if the reset worked (stopped dropping internet). Also look at resetting your DHCP server and make sure you have enough addresses to hand out for the number of devices you have.
HELFIT

ASKER
There are enough addresses. This happened on another workstation. I've learned that the workstation can ping the gateway but the gateway can't ping the workstation when they lose their internet connection.
⚡ FREE TRIAL OFFER
Try out a week of full access for free.
Find out why thousands trust the EE community with their toughest problems.
John

What owns DHCP?   Server or Router?
What owns the Gateway?  Router probably.

You might want to see if there is a firmware update for your router, update it and reset it. You might want to reset to factory settings and set it up again.
HELFIT

ASKER
DHCP is runs on a windows server within the domain. This happens on workstations that have a static ip address as well. Router is a Cisco switch. factory settings is not an option.
HELFIT

ASKER
What is confusing me now is that the workstation can ping the gateway, but the gateway can't ping the workstation.
I started with Experts Exchange in 2004 and it's been a mainstay of my professional computing life since. It helped me launch a career as a programmer / Oracle data analyst
William Peck
John

Something appears to have gone screwy with the Cisco router.

I also suggest you find a break in time and restart the Server. Caution: If you have not restarted the Server recently, it will be 9 months pregnant with updates. It just may need to apply updates.
Benjamin Van Ditmars

if the client can ping the firewall and the firewall cant ping the client back. i hope you shutdown the windows firewall. then it looks like an arp problem. can you look at the arp table in the firewall and find the reservations for the clients that cant access the internet. and see if the showed mac-address is correct. if not. flush the arp cache of the router