Redirect a private IP always to the same public one

RouterOS Beginner Basics
1

Hey everybody!

We have two different service providers, and some of our internal clients have to always use one of the WAN interfaces (the one we have a fixed public IP).
Currently, there’s only one internal client that need that. For that reason, I fixed it’s IP in the DHCP server config (using leases → make static), and I added a srcnat rule in the firewall (action=srcnat, to_addresses=desired public ip).
The trick worked, but the performance of that link was worsened a lot (it was really much slower).
Do you have any idea of what may be the problem?

I’m a newbie in configuring router, so maybe this is a basic question.

Thanks in advance!
Ivan

P.S.: We need to redirect some internal clients to the public IP address, just because they have to communicate with an external client that have withlisted the fixed IP provided by one of our ISP, and the other one is not whitelisted. In the future, we will properly configure VLANs to solve the problem, so our the internat clients that need this are “wired” just to one of the WAN interfaces.

2

Policy routing rules is what you should use…
So under IP route rules, for that src address select a table with name lets say ISP2.
Now in the IP routes, create a default route with routing mark ISP2.
That way, this client will be always get routed through that Table.