A: For major ISPs, every 3–6 months. For generic models, 1–2 times per year.
A: It may work but could break VoIP, VLAN tags, or TR-069. Worse, it might lock your device to generic mode, losing carrier aggregation profiles. Stick to ISP-provided firmware. zyxel nr5103e firmware
Security vulnerabilities, ISP lockouts, voided warranty. A: For major ISPs, every 3–6 months