Dear @Boriy ,

Boriy wrote

But ISP told us, it can only give us 100mb/s per port, when our router connected to their Switch. But they said, we can take also 2nd port on their switch, so we will have 2 ports with 100mb/s each, but with different PPPoE.I've never used Load Balancing before, but if it can speed up our internet speed from 100mb/s to 200mb/s, that would be great.Currently, we have UniFi Dream Machine Pro as our main router, but it does not support load balance.Can we put TL-R470T+ a top of our router, so our main router will have 200mb/s ?

In general, Load Balance works mainly to improve utilisation, not to overlay bandwidth 1+1=2 effects.

Please check the details as follow:

When the load balance is disabled, the data packets will pass through WAN1 and WAN2 randomly, when the load balance is enabled, the router will decide which WAN entry the data packets should pass depend on the bandwidth we set for each WAN link.

For example, the bandwidth used by WAN1 is X1, and the bandwidth used by WAN2 is X2, the total bandwidth of WAN1 is Y1, the total bandwidth of WAN2 is Y2. So let suppose c=x/y, the WAN link who has lower c value will have more data traffic to handle for the next moment. But it doesn't mean you can get 200Mbps speed.

Best Regards!

@Boriy 

I won't set up like this. Double NAT will wreck your internet surf experience. No gamers like this. And double NAT can also causes problem with load balance. I remember dream machines is a well-rounded router. No way that does not support load balance.