2 Wan - Guaranteed minimum bandwidth to server

RouterOS Beginner Basics
1

I have 2 Wan in load balancing using PCC. A classic setup using mangle marking rule.
In the lan i have a server that can be reached from internet through a dsn-nat that is working.

During high bandwidth usage from other clients of the LAN, requests to the server from internet can do a timeout error.
I have to guarantee a minimum bandwidth to the server.
WAN1 is a 30M down/ 3M up
WAN2 is a 20M down/ 2M up
Server IP 192.168.1.200

Can be done with simple queues on interface WAN1 and WAN2 ?
Other ideas on how to guarantee a minimum bandwidth ?

2

If i add a simple queue for each WAN interface:

/queue simple
add max-limit=3M/30M name="WAN1" target=192.168.1.0/24
add limit-at=1M/1M max-limit=0/0 name="SERVER Traffic" parent="WAN1" target=192.168.1.200
add max-limit=3M/30M name="Other client" parent="WAN1" target=192.168.1.0/24

Can it work or i have to specify the interface ?

I know i can regulate only the upload. Download will be decided by the ISP.