Large amount (80-99%) of packet loss, but fixed by ARP Ping

Hello,

I have a situation I have not encountered before. I have a fairly simple network VLAN setup. A CHR instance has an interface VLAN numbered 123. It has a LAN Address and a DHCP server to establish this VLAN network.

CHR (Interface VLAN 123) → CRS Switch → CRS Switch → hAP Lite → Port 3 (Untagged PVID 123) → Raspberry Pi

The issue is, after exactly 15 seconds, the CHR loses connectivity with the Raspberry Pi. The issue is resolved when I do an ARP ping, but the problem returns 15 seconds after I stop ARP Ping.

What is going on? How do I fix it? I’m experienced with routing, but layer 2 has been a bit of a mystery to me.

Screenshots:
First one is packet loss right as it happens. Second one is connectivity restoration right after I do an ARP Ping.
Screenshot 2024-02-16 005048.png
Screenshot 2024-02-16 005457.png