No Default Routes present when using Multi WAN

[Tech_Gadget2]

Hello folks,

I am running OPNsense Business Edition and the update from v23.4 (v23.1.5 CE) to v23.4.2_1 (v23.1.11 CE) last September broke my Multi WAN setup. I just updated to v23.10.1_2 which correlates to v23.7.10 CE and my problem still persists, so now I thought let's fix the issue for good.

Status Quo:
- one physical interface, where I have setup two VLANs which are the uplinks to my ISPs
- the IP addresses on these VLAN interfaces are statically assigned IPv4 (IPv6 disabled)
- two single gateways setup, for each of them "Upstream Gateway" is checked
- one gateway group configured and used in many firewall policies
- end devices have internet connection just fine, so the gateway group in the firewall policies is considered and the traffic is routed properly

Problem:
- the firewall itself has no internet connection preventing the system to reach the OPNsense update repositories and also breaking my Unbound DNS Blocklists, since the cronjob can't update them anymore

Root Cause:
- after the update to v23.4.2_1 (v23.1.11 CE) there are no default routes present in the routing table anymore

Workaround (temporarily):
- since September I have a workaround in place, I've configured a static default route via CLI pointing to my main ISP
- the problem here is that now the firewall itself is not using Multi WAN anymore, so when my first ISP fails I have the above mentioned problem again
- the second thing I observed is that even this statically default route is lost again after a while (even without any reboot of the firewall)

My own research so far was unsuccessful. The most promising hit so far was this forum post, but I checked my configuration.xml and there are no duplicate gateways present, so back to square one.

I am open for any input on how to proceed further with this issue.

Regards
Nick

[Tech_Gadget2]

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