Mikrotik PPPOE connection with no download (rx) traffic at random times

Hello everyone,

I have set up 3 pppoe-client connections on the same ethernet port (ISP providing me with 3 different accounts on same link).
I use PCC to distribute the traffic between all 3 connections equally.
Everything seems to work fine but sometimes we experience a loss in connection and when I check my Mikrotik interfaces, all 3 pppoe interfaces have an Rx of 0 for a few seconds (10-15 seconds) and then everything gets back to normal and connection is back.

Keep-alive timeout is set to 30 seconds. If I decrease the keep-alive timeout to less than 10 seconds, connection to pppoe is lost and will reconnect after 30 seconds.
I can keep the keep-alive timeout to 30 seconds but the problem is that even with that, clients are losing connectivity for 10-15 seconds and this is really frustrating.

Is this problem coming from my ISP (link problem, disconnection) or is there a problem in my configuration?
If there is a configuration error, it wouldn’t work at all no?
Any chance there is a loop happening randomly in the network and causing this?