Score:3

ARP keeps getting old/wrong MAC address for gateway

cl flag

We have implemented a new firewall.

My clients (Windows 10/11) and servers (Windows Server 2012R2) are randomly disconnecting from internet.

If I do an arp -d, then my gateway (10.0.0.1) MAC is ac-xx-xx-xx-xx-81 and I can't access the internet - I get a Reply from 10.0.0.1: Destination net unreachable..

After like 10 seconds I get internet back and everyting works perfectly. If I do a "arp -a" and now my 10.0.0.1 MAC address is 6a-xx-xx-xx-xx-de.

If I eg. tries to open a TeamViewer connection to a client, then MAC jumps back to ac-xx-xx-xx-xx-81 again and I loose internet connection for like 10 seconds.

Even though I have cleared the ARP, I keep randomly getting wrong MAC address for my gateway.

Any idea how I can erase the wrong MAC ac-xx-xx-xx-xx-81 from the entire domain?

in flag
Is it possible you have a second device with the IP address of your gateway?
cl flag
@GeraldSchneider ... YOU ARE MY HERO! And I'm slapping my head so hard that I should not be working in an IT department! The old firewall was still connected - man I feel dumb ... but you really saved my day!
in flag
I turned the comment into an answer so you can accept it. Questions without an accepted answer stay in the system as "unsolved".
Score:8
in flag

Make sure you don't have another device active that has the IP of your gateway.

mangohost

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