The method was called but missing — always raised AttributeError, so
Fix SNMP did nothing on OpenWRT devices.
OpenWRT's default firewall (fw4) policy-drops everything except the
ports explicitly listed in the management zone (SSH/HTTP/HTTPS/ICMP).
SNMP (UDP/161) is not in that list, which is why snmpd runs but is
unreachable from outside the device.
Fix adds a persistent UCI firewall rule for UDP/161, reloads fw4
immediately, verifies snmpd is running, and probes locally if SNMP
client tools are available. Returns success so callers can clear the
snmp_no_data warning.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
