Issue with DHCP6 client on WAN - it works until the first system reboot

[guest37312]

Hello! I'm facing a weird issue with IPv6 on my OPNsense router.

Whenever I configure IPv6 with DHCPv6-PD over a separate PPPoE tunnel to my ISP, it works correctly, I get `/56` prefix, gateway and DNS information from the DHCPv6 server in my ISP's network, and my LAN interface gets address with Track Interface option.

This all works until I reboot my router or edit the interface in any way (even something irrelevant like interface name). Then it stops working for seemingly no reason and won't come back until I literally return OPNsense to factory defaults and re-configure everything from scratch. This pattern happened to me at least 2 times and yesterday was the 3rd one which made me write here.

Perhaps someone will know how to fix it.

System info:

• OPNsense 23.1.2-amd64
• Lenovo ThinkCentre M73 SFF
• Intel i3-4130
• 8GB DDR3 RAM
• Intel i340-T2 NIC

Interface settings:

• LAN
  
  
  
  • IPv4: Static address
  • IPv6: Track Interface
    
    
    
    • WANv6
    • Prefix ID 0
    • Allow manual adjustment of DHCPv6 and Router Advertisements
• WANv4 (pppoe0)
  
  
  
  • IPv4: PPPoE on vlan01
  • IPv6: None
• WANv6 (pppoe1)
  
  
  
  • IPv4: PPPoE on vlan01 (different username)
  • IPv6: DHCPv6
    
    
    
    • Request only an IPv6 prefix
    • Prefix delegation size `/56`
    • Send IPv6 prefix hint
    • Use IPv4 connectivity
• VLAN01
  
  
  
  • Tag 35
  • Priority 0
  • Parent: physical WAN port connected to fiber ONT

Steps to reproduce:

• Save listed configuration
• See Interface overview
  
  
  
  • WANv4 correctly gets IPv4 address and info
  • WANv6 correctly gets IPv6 prefix and info (both PPPoE and DHCPv6 up)
  • LAN correctly gets IPv6 address from WANv6
• Reboot system
• See Interface overview again
  
  
  
  • WANv4 correctly gets IPv4 address and info (no change)
  • WANv6 has PPPoE up, DHCPv6 down, only gets IPv6 gateway
  • LAN doesn't get IPv6 address

In case it helps, my ISP is Orange Poland and I use their gigabit FTTH service.

I had identical configuration on pfSense and it worked without issues for months. Problems begun only after I recently switched to OPNsense. What makes my head blow the most is the fact that this configuration works fine but only undergoes spontaneous combustion when I reload interface or reboot system, with no other change involved whatsoever. It happened when I just changed the interface name, then when i rebooted the system for an unrelated reason and now when I updated OPNsense.

I looked for `dhcp6c` in Log Files -> General, but there's nothing in there despite IPv6 DHCP log level being set to "Debug". I also have "Prevent release" option enabled.

Thank you in advance for any help on this one.

[pataps]

That is truly lucky and unfortunate at the same time...

Im having exactly the same issue, unsurprisingly with same ISP. But in my case what solves this is setting LAN ipv6 setting to something else, like SLAAC, applying changes and setting back Track interface.

Even if there's single ipv6 only WAN with PPPoE effect is the same, so the other WAN connection mentioned in OP doesn't matter. PPPoE is up but ipv6 is not delegated to LAN.

Even if this is something specific to this ISP, I managed to get this working without issues on Unifi router so it can work.

Any ideas on how to investigate this and narrow down the issue would be appreciated!