hi guys
we have been investigating an issue in our WISP with CPEs is not able to negotiate full payload pppoe connections ,
our wireless gear is UBNT and our Core is Mikrotik CCR 1036
below is a link to a post of the issue where we confirmed with UBNT support that Mikrotik pppoe server is actually NOT following RFC 4638 (Accommodating an MTU/MRU greater than 1492 in PPPoE) as its response to CPE request is missing ppp-max-payload tag
http://community.ubnt.com/t5/airOS-v5-Beta/5-6-1B2-pppoe-wont-support-full-payload-1500Bytes/m-p/1213518/highlight/false#M21112