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I have pihole (DHCP enabled) in my raspberry Pi. In my Macbook, I have IPV6 disabled and I use VPN as and when needed. When I use the router’s default DHCP, VPN connection stays until I disconnect. When using pihole’s dhcp, VPN disconnects every 5 minutes and reconnects. With tcpdump, I see a correlation between Macbook’s DHCPRequest to Pihole’s DHCP server and VPN connection drop. In Pihole DHCP server, my lease time configuration is 168 hours.
[VPN should not disconnect]
[Every 5 minutes VPN disconnects and reconnects]