How to deal with the routing of pptp traffic of Mikrotik clients?

Question

network hardware

Given: Mikrotik
ether1 - LAN + Internet access
ether4 - LAN without Internet access
ether1 and ether4 are on the same subnet and receive settings via dhcp.
Raised pptp server, subscribers cling to ip which is on ether4.
The problem is that the traffic of pptp clients (enters and exits :)) through ether1, it can be seen from rx/tx.
How to implement that pptp client traffic would come to the router on ether4 and go online through ether1???