If possible, put a network tap in-between the router and the ONT, and sniff the traffic. I've seen this recently where in a very specific circumstance (two hardware vendors, and only with CGNAT IPs), one side stopped responding to ARP requests. The tap capture showed the request going out, but the far end never processed it. Running a capture on the far end device wouldn't show the received ARP request - it just vanished somewhere between the wire and the pcap. Solution ended up being a software update on the router side, I'm assuming it updated a NIC driver as well. -----Original Message----- From: NANOG <nanog-bounces> On Behalf Of Neil Hanlon Sent: Friday, July 14, 2023 10:54 AM To: Mel Beckman <mel@beckman.org> Cc: nanog@nanog.org Subject: Re: Request for assistance with Verizon FIOS connection CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.