Read this to see if it helps. http://www.tp-link.com/en/article/?faqid=715

It was the same link I pasted in my post which I already followed!

Raj,

Speedtest works by opening upto 4 sessions (threads) to the speedtest server. The maximum bandwidth will be seen if 2 sessions get routed on WAN1 and 2 on WAN2. However, the WAN port that gets assigned to a session is not deterministic, rather it is statistical, and the load balancing router tries to maintain the ratio of bandwidths as configured by you IN THE LONG RUN. When the 4 sessions to the speedtest server are opened, it is very likely that all 4 sessions get assigned to the same WAN port. When that happens, all 4 threads are trying to download/upload traffic on 1 WAN link, and as a result you see the bandwidth of one of the WAN ports. In practice, although the speedtest doesn't show you the sum of bandwidths, you should get the clubbed speed. One good test is to download a well seeded torrent - the torrent will open multiple sessions, and statistically, the sessions will get spread across the two WAN ports. Hope this helps.

The only way to bond or aggregate multiple internet connections is through VPN bonding or MLPPP. Currently only a few DSL providers support MLPPP but require a CPE device that has MLPPP capability in order to get it to work. VPN bonding requires a VPN provider that supports this feature. In both these scenarios the potential of aggregating two or more internet connections can result in cumulative download and upload speeds respectively. TP-Link products do not currently support either of these features.

you right, in torrent i got full speed for download/upload but not in speedtest website