There are plenty of good tutorials how to create a L2TP/IPsec VPN or OpenVPN on Mikrotik, though not many mention what rule you need in your firewall if you wan to be able to access devices on the local network of the VPN server. Some say that you need to enable proxy-arp on the local device, nope, that’s not the proper way. It is worth mentioning that this is on Mikrotik OS 6.37
This is the rule you need to add to your firewall, of course replace the network with yours assigned to VPN clients
ip firewall nat add action=masquerade chain=srcnat dst-address=!192.168.1.0/24 src-address=192.168.1.0/24