In the past i had a similar problem
http://forum.mikrotik.com/t/acces-modem-on-wan-side-from-lan-side/33850/1
Perhaps you can change the lan ip range temporarily if that presents a problem.
In the past i had a similar problem
http://forum.mikrotik.com/t/acces-modem-on-wan-side-from-lan-side/33850/1
Perhaps you can change the lan ip range temporarily if that presents a problem.