Thanks to @Amm0 s post at http://forum.mikrotik.com/t/zerotier-2-local-subnets/170858/1 i added /ip/firewall/nat/add action=masquerade chain=srcnat out-interface=zerotier1 place-before=0 (out-interface=ether1 did not work) and now i can work connect to the OFFICE network and ping (and http).
BUT: Int he office there is a device whos doing udp broadcasting (this is why i need zerotier layer2). The client normaly sees this brodcast and knows the device. I cannot see the device in the app. so it looks i dont see the traffic..
One problem solved.. now anotherone…