ARP Attacker

[Banal 0]

ESET has notified me that 192.168.49.1 is sending malicious traffic on my LAN.  I do not see any such device connected to my network when I look at my router.  I did a little searching and it was suggested that I go to a command prompt and issue the "arp -a" command and it will list IP addresses along with the MAC addresses.  The suggestion was that if I find any MAC address duplicates that it is probably the source of the attack.  So I did and there it was.  192.168.49.1 is sending the traffic that EST is warning me about.  It has the same MAC as the device on my network with IP 192.168.1.245 which is one of my Amazon Fire boxes.

My questions are:

1.  Do you think I have reached the correct conclusion that the device is the source of the problem?

2.  Do you have any suggestions on how I can fix the problem?

3. Is this a problem I should be concerned about?

Thank you very much!