Link Load Balancing enables you to use multiple internet access line on a site to provide additional bandwidth. This is a good way to use cheaper ADSL lines which are available in some regions.
When an end-user device uses the internet it generates a server request that is sent out over a single Internet access line. As a result, the file download will only use a single Internet access line, even though the other available Internet access lines may be idle. This is because there is no bandwidth aggregation/bonding on WAN interfaces. for example adding two lines at 100Mbps each will not give a user device 200Mbps on a speed test - you will still see 100Mbps. If you need bonding you may want a dedicated appliance like Elfiq or Mushroomnetworks. Devices are allocated on a round-robin based on IP to each available line.
Connected Line Limit
There is no theoretical limit. You will, however, be limited by the number of available interfaces on the MikroTik. Every MikroTik interface, in theory, can be assigned to be a WAN interface. The template provided by Airangel has eth1 and eth2 dedicated to be WAN interfaces, however, you can configure additionally available interfaces as you see fit.
This is the physical interface speed of the MikroTik. If the MikroTik ports are 1Gbps, this will be your maximum speed.
In Captivnet, navigate to: Asset>network>network section. You will need to add an additional interface and set it’s role to WAN. From there, you would configure a new WAN interface same as you would for WAN-1. Once configured saved and published, Mikrotik will start automatically load balance traffic on each WAN interface.
By default, traffic is balanced at equal cost across all connected WAN interfaces. To change this, you can configure the balancing weight by adding the same interface more than once in the network>load balancing list. Each additional interface adds more weight to balancing on the particular line. For example, you have connected WAN-1 and WAN-2 interfaces and the default rule is balancing 50/50 between both. In this situation you want WAN-1 to be prioritised because line quality is higher. Add WAN-1 into load balancing again and your balancing now changes to 66% to WAN-1 and 33% to WAN-2 of total traffic.