Mikrotik recommends a max-mtu of 1480 as the optimal value. However most ISP's recomend 1492 for ADSL (1500-8 bytes overhead for PPPoE). If my ISP recommends 1492, should I still set the value of 1480 on my Mikrotik as per the Mikrotik documentation?

Use the largest value that works for you. On occasion I've had to go as low as 1360 to get certain sites to work.

Regards

Andrew