@Yannie Thanks for reply. When WAN ISP network was down, I tried the link backup but it did not work. I was getting no reply to ping even with link backup configured. Also problem with link backup is...

WAN = Static IP address to WAN ISP router. --> ISP OR Dyanmic IP address from WAN ISP router WAN DNS = 8.8.8.8 WAN/LAN1 = PPOE WAN connection directly into er605 from ISP WAN/LAN1 = 8.8.8.8 Enable...