I have 2 routers. One core router which is doing all the firewall, nat etc. and the other router on which I run 3 DHCP servers. The addressing on the 2nd router is set to STATIC.
What happens is that sometimes for no reason PC loses internet connection. The IP is there but I can’t ping anything. The only way I can make it to work again is to set a dummy MAC address to PC’s NIC eg. 00:AA:CC:DD:EE:FF and of course also set it in the Mikrotik static lease. After that internet works again on that same PC with the same IP. Really weird.
RouterOS version is 6.20. I know it’s not the latest one but my domain server (Samba4) works properly with this RouterOS version. Once I did an upgrade and I had problems with DNS resolving.
Did anyone had the same problem with this MAC thing? Please help!
Duplicate MAC address on network may cause this.
Network loop could also cause this.
When your PC loses internet connection, check the arp tables on your PC and Mikrotik.
On Windows in a command window, enter arp -a
Do you see your router’s IP listed with MAC address?
On Mikrotik, go to IP > Arp, do you see your PC IP in there with MAC and also the correct interface?
If you don’t see an arp entry in either or, then you can use wireshark to see if arp lookups are working.
Start wireshark, then ping the router. In wireshark you should see arp packets where your PC sends out a request asking who has IP xxxx Then the router should reply saying it does. Then the ping gets sent.
I’ve checked for duplicate MAC addresses and there are no any duplicates 100%.
Also, it’s not a network loop 100%, I have a email notification coming if there is a loop in the network.
I haven’t checked the ARP table but if it happens again I sure will and also I will try with Wireshark.
Could it be something with the managed switches? This is only happening in one building which has managed switches.
I must note that this started to happen since the last couple of months, never before.
Any other opinions? You guys feel free to write here.