We are using mikrotik 2.9.23 on an Intel p3 platform. We only use this box as a pppoe concentrator with about 300 pppoe clients. We are using no wireless interfaces just bridging between two Ethernet interfaces. The pppoe server is assigned to the bridge interface. We have had this in line for about 3 months with only 2 problems which hopefully someone can help us with.

First, periodically we will notice that each client either connecting via pppoe or just transiting through one Ethernet interface to the other via the bridge will slow down to a fraction of their available bandwidth and data transfers are very bursty and uneven. Rebooting does not solve the problem but if we change the mtu on all 3 interfaces and then change it back it works fine again and transfers are smooth and much much faster.

This leads me to our only other problem. When we reboot the mikrotik or otherwise disconnect all users when the box comes back up all 300 clients try to authenticate at once which overwhelms our radius server. We cannot use another brand of radius server because it goes with our billing platform. Is there any way to send authentication requests from the pppoe concentrator in a slower fashion rather than all at once. Can we specify multiple radius servers?

Thanks in advance

What kind of PPPoE clients are used?

Try break the bridge and set up two PPPoE server instance with different service names, if you need traffic between the interfaces set up routing

For the RADIUS part, try reduce connection between MT and RADIUS with firewall rules.
/Paul