Hi
I have 2 ISP providers and one LAN network. One of ISPs is main and all traffic going through it. Another i use automatically when main ISP is not reachable. Now i need to route all traffic from some PCs in my LAN(192.168.88.x) trough second ISP.

At first, i created new Address list (Firewall > Address List) which named "CRM". I added all IP address of PCs in my LAN which i need to route trough second ISP.
After that, i created mangle rule:
chain="prerouting" sourse-adr-list="CRM" action="mark routing" new routing mark="CRM_mark"

Then, i created new route. I attached screenshot of this route (new route) and all my routes in the system.

But after, i did all of this steps this PCs had not access to internet. Other PCs, except this PCs, in my office had access to Internet, as usual.

How can i implement my plan?

Try to find the answer in this post.

I Solved this problem with this action: changing gateway interface on IP address of gateway.