Dear @jhunjhun,
i Have got a BSNL Fifth connection which has input as fiber optic and Other is Airtel which provides WAN connection
How can i convert the fiber optic to WAN for load Balancing ?
The TL-R480T+ router only has RJ-45 ports, which can connect via Ethernet cables only.
If the ISP provides the Internet service with fiber cable instead of Ethernet cable, you may need a fiber modem to convert the Fiber connection to an Ethernet connection first and then connect to WAN port the TL-R480T+ router with an Ethernet cable for Internet access. Usually the ISP would offer a fiber modem, you may contact the ISP to confirm it.
By the way, you may note that the TL-R480T+ only has 100Mbps Ethernet ports, so the maximum throughput is no more than 100Mbps.
If your ISPs provide you more than 100Mbps bandwidth, you may consider upgrading to a more powerful router.