IPSEC OSPF opnsense 26.7

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Describe the bug

Hi!

I upgraded to 26.7 and now OSPF in IPSEC dosent work for me.

I have an IPSEC VTI tunnel to a cisco router, the cisco router initiates the connection and the tunnel itself works. Since the update, OSPF just stops working some minutes and then comes back to life.

I see this in the OSPF logs - *** sendmsg in ospf_write failed to 224.0.0.5, id 0, off 0, len 120, interface ipsec10, mtu 1400: Network is unreachable

The network type is Point-to-multipoint and eveything worked before the upgrade.

To Reproduce

Run OSPF over IPSEC VTI in OPNsense version >= 26.7.

Expected behavior

OSPF should form and exchange routes.

Describe alternatives you considered

A clear and concise description of any alternative solutions or workaround you considered.

N/A

Relevant log files

If applicable, information from log files supporting your claim.
Log from FRR

2026-07-16T17:35:38
Error
ospfd
*** sendmsg in ospf_write failed to 224.0.0.5, id 0, off 0, len 120, interface ipsec10, mtu 1400: Network is unreachable
2026-07-16T17:35:38
Notice
ospfd
AdjChg: Nbr 172.28.0.29, NbrIP 172.28.0.21 (default) on ipsec10:172.28.0.20: Exchange -> Full (ExchangeDone)
2026-07-16T17:35:38
Notice
ospfd
AdjChg: Nbr 172.28.0.29, NbrIP 172.28.0.21 (default) on ipsec10:172.28.0.20: Full -> Deleted (InactivityTimer)
2026-07-16T17:34:58
Error
ospfd
*** sendmsg in ospf_write failed to 224.0.0.5, id 0, off 0, len 120, interface ipsec10, mtu 1400: Network is unreachable
2026-07-16T17:34:58
Notice
ospfd
AdjChg: Nbr 172.28.0.29, NbrIP 172.28.0.21 (default) on ipsec10:172.28.0.20: Exchange -> Full (ExchangeDone)
2026-07-16T17:34:58
Notice
ospfd
AdjChg: Nbr 172.28.0.29, NbrIP 172.28.0.21 (default) on ipsec10:172.28.0.20: Full -> Deleted (InactivityTimer)
2026-07-16T17:34:18
Notice
ospfd
AdjChg: Nbr 172.28.0.29, NbrIP 172.28.0.21 (default) on ipsec10:172.28.0.20: Exchange -> Full (ExchangeDone)
2026-07-16T17:34:18
Notice
ospfd
AdjChg: Nbr 172.28.0.29, NbrIP 172.28.0.21 (default) on ipsec10:172.28.0.20: Full -> Deleted (InactivityTimer)
2026-07-16T17:33:38
Error
ospfd
*** sendmsg in ospf_write failed to 224.0.0.5, id 0, off 0, len 120, interface ipsec10, mtu 1400: Network is unreachable
2026-07-16T17:33:38
Notice
ospfd
AdjChg: Nbr 172.28.0.29, NbrIP 172.28.0.21 (default) on ipsec10:172.28.0.20: Exchange -> Full (ExchangeDone)
2026-07-16T17:33:38
Notice
ospfd
AdjChg: Nbr 172.28.0.29, NbrIP 172.28.0.21 (default) on ipsec10:172.28.0.20: Full -> Deleted (InactivityTimer)
2026-07-16T17:32:58
Notice
ospfd
AdjChg: Nbr 172.28.0.29, NbrIP 172.28.0.21 (default) on ipsec10:172.28.0.20: Exchange -> Full (ExchangeDone)
2026-07-16T17:32:58
Notice
ospfd
AdjChg: Nbr 172.28.0.29, NbrIP 172.28.0.21 (default) on ipsec10:172.28.0.20: Full -> Deleted (InactivityTimer)
2026-07-16T17:32:28
Error
ospfd
*** sendmsg in ospf_write failed to 224.0.0.5, id 0, off 0, len 120, interface ipsec10, mtu 1400: Network is unreachable
2026-07-16T17:32:28
Notice
ospfd
AdjChg: Nbr 172.28.0.29, NbrIP 172.28.0.21 (default) on ipsec10:172.28.0.20: Loading -> Full (LoadingDone)

Additional context

Add any other context about the problem here.

Environment

Software version used and hardware type if relevant, e.g.:

OPNsense 26.7

Start by reproducing OSPF over an IPSEC VTI on OPNsense 26.7 or later, using the FRR ospfd log and the ipsec10 interface details provided. Investigate the repeated “Network is unreachable” errors and adjacency transitions; done means OSPF remains established and exchanges routes without recurring inactivity timeouts.