pfSense

Confirming this issue still exists.

Per RFC 4861 §4.2, a Router Lifetime of 0 indicates the router should not be considered a default router, while still allowing it to advertise prefixes and RDNSS options. This is the correct configuration for networks using ULA-only addressing with SLAAC where no IPv6 default route should be installed on clients.

The GUI at Services → Router Advertisements rejects a value of 0 for "Router lifetime" with the HTML5 validation popup: "Please select a value that is no less than 1."

This looks to be a regression. It was previously resolved in Bug #7502, which was addressed in 2.4.3 by allowing min=0 on this field.

The regression was likely introduced by Bug #12439 (https://github.com/pfsense/pfsense/commit/7cf69c985d73), which added blanket input validation (min=1) to all RA lifetime fields without accounting for the fact that Router Lifetime (AdvDefaultLifetime) specifically permits 0.

Workaround: edit the config XML directly to set <raadvdefaultlifetime>0</raadvdefaultlifetime> — the backend radvd config generation implicitly handles 0. Avoid re-saving via the RA GUI page afterward.

Suggested fix - in services_router_advertisements.php

• Change the HTML input's min from 1 to 0 for the raadvdefaultlifetime field
• Modify the PHP validation to explicitly handle 0 — change the guard to use isset(), and allow < 0 as the lower bound

Related: #7502 (original fix), #12439 (introduced regression)