Uh, yes.
My MTik is RB951G with two LTE usb dongles that assign private IPs (dhcp) to the Mtiks lte interfaces. So mtik lte1 interface has private IP 192.168.8.100 and lte2 has 192.168.51.238.
Corresponding routes:
/ip route
add comment="LTE2 for l2tp ipsec client" distance=1 gateway=192.168.51.1 routing-mark=markforl2tp
add comment="LTE1" distance=1 gateway=192.168.8.1
add comment="LTE2" distance=2 gateway=192.168.51.1
are defined and everything works baside the thing that I want to force mtik l2tp/ipsec client to go exclusively through lte2 interface. When the l2tp client is enabled, the ipsec always goes through lte1 interface so ipsec active peer has local ip 192.168.51.238 and remote ip is the public ip of the server. In that situation l2tp can not be established over lte2 as ipsec is established over lte1 so it hangs. If I completly disable gateway 192.168.8.1 over lte1 interface, leaving only lte2 gateway enabled everything works perfectly.
EDIT: Similarly, if I completely disable gateway 192.168.51.1 over lte2 interface again everything works.
What should I do to accomplish what you said that “the whole network plus the interface is in the rule” ?