Mikrotik has a great way to do simple equal sharing of bandwidth using PCQ queues.
Basically it decides the available bandwidth between the active devices.
To make it work you need to define your maximum upload and download bandwidth. Because you can’t really shape traffic that has already arrived at your interface, you need to set your download limit to slightly less than your ISP is actually providing.
add max-limit=10M/9900k name=internet-queue queue=pcq-upload-default/pcq-download-default target=eth2