MikroTik

I am having a problem.. yes that's why i am here. It started a few weeks back and i cant find what is causing the problem I have seen other persons with similar problems and none of the suggested solutions have worked Here goes.
I have 36 persons connecting using PPPOE with userman as the radius server which has worked fine for the pas year and half without any problem except the 5 hour difference in the Userman time and the router time(i have adapted to that) Recently I started seeing users disconnected and not able to reconnect.
I am using 6.42rc28 on RB2011UiAS-2HnD to host the userman
persons are connecting with ubnt airgrids 2.4ghz to 120 sectors connected to Mik RB750g routers that are then connected to the RB2011.

I realised something from trial and error when persons get disconnected if i disable the router in userman for a while then enable it some persons will get on. That's how i have been able to get users reconnected.

I have tried using a loopback address for the router.
I have changed the timeout for radius on the router to values from 200 to 4000 after the last firmware update it started complaining about values over 3000

Any help would be appreciated

Heay.. Did you get any solution or workaround to this problem . I am having the same issue with PPTP VPN