I use ER605 (still on v1.1.1) in standalone mode with 2 WAN ports. These two internet connections have identical bandwidth plan.

I have set up Bandwidth Control when usage reaches a certain percentage (e.g. 80%, later tried 90% as well) to avoid any user overloading the traffic to internet.

I need to understand the mechanism how it works in practice in order to be able to set it the most optimized way, with a certain percentage value.

First of all, I guess the reaching percentage is defined in Bandwidth Control when more than one user is occupying the bandwidth in the same time, otherwise it wouldn't make sense.

Does this value means on each WAN ports independently?

(I set it up for each WAN ports separately (because in the past the WANs had different "speed") but I know I could have defined them in one single rule as well.)

Due to the Load Balance function activated, it's not clear for me, how the router defines bandwidth usage.

It's because the logical method should be, the router providing different WAN ports for simultaneous traffic requests following Load Balance rules first.

So, when will the usage reach the defined value?

Does it get activated only on that WAN port where the traffic is that heavy?

Does Load Balance try to handle the situation first, distributing bandwidth wisely and only after that gives the control to Bandwidth Control function? (I guess so)

Unfortunately Traffic Statistics page shows unreliable and vague usage values, so that doesn't help to figure it out.

Recently when several more-active users are connected, Bandwidth Control gets activated, even when Statistics doesn't show that high usage. So, I wondered why in the past it had been activating this function less often.

The internet traffic has had no freezing so far, it's just a bit annoying when a user is compelled to get the limited bandwidth when Statistics page doesn't show not even close to the max bandwidth usage.