Hello,
I have identified what appears to be a regression in OPNsense 26.7 related to gateway monitoring and default route installation.
My configuration is:
* Physical interface: `igb4`
* Gateway: `192.168.11.1`
* This gateway is configured as the system default gateway
* Monitor IP: `195.201.128.208`
* Gateway monitoring enabled
After upgrading from OPNsense 26.1 to 26.7, the default route is no longer installed correctly during boot.
The Monitor IP host route is created correctly:
```text
195.201.128.208 192.168.11.1 UGHS igb4
```
However, the expected default route is missing:
```text
default 192.168.11.1 UGS igb4
```
The gateway log repeatedly shows `dpinger` errors such as:
```text
sendto error: 50
sendto error: 64
sendto error: 65
```
The Monitor IP is reachable, and the static host route correctly forces it through `igb4`.
If I disable and re-enable the gateway from the GUI, the default route is immediately installed.
If I disable gateway monitoring and reboot the firewall, the default route is installed correctly at boot.
The issue can therefore be reproduced with a single Ethernet WAN and appears to be specifically related to gateway monitoring or `dpinger` initialization.
Steps to reproduce:
1. Configure an Ethernet WAN with a static gateway.
2. Set that gateway as the system default gateway.
3. Enable gateway monitoring.
4. Configure a Monitor IP.
5. Reboot the firewall.
6. Verify that the Monitor IP host route exists.
7. Verify that the default route is missing.
8. Disable gateway monitoring and reboot.
9. Verify that the default route is now installed correctly.
This configuration worked correctly on OPNsense 26.1. The issue started after upgrading to OPNsense 26.7.
Current workaround:
* disable gateway monitoring on the default gateway.
This restores the default route at boot, but removes upstream connectivity monitoring.
It appears to be a regression or race condition in the interaction between gateway monitoring, `dpinger`, and default-route installation during system startup.
to complete information, on firewall there are also wireguard tunnels (without overlapping of course 192.168.11.0/24)
Could be this one we just unearthed:
# opnsense-patch https://github.com/opnsense/core/commit/94b3771b
Cheers,
Franco