Interconnect two different network

Hi,
I need some suggestion to solve this issue: I have the main LAN network (10.5.17.0/24, with gateway 10.5.17.1) and a secondary network (192.168.88.0/24 with gateway 192.168.88.1).

I need that the host connected to 192.168.88.0/24 network can contact devices (printers) and server on network 10.5.17.0/24 but the internet connection must be direct (it have not pass throught 10.5.17.1)
.
The 192.168.88.0 network have following router RB2011UiAS-2HnD.

I tried to assign on eth10 the address 10.5.17.250 and I created the route tables but, most probably, I done some error because do not works.

Someone could help me to configure properly the router to solve this issue ?

Just to be clear.
You have ONE router and behind that router you have two networks/LANs
(assume one is on a bridge and the other not, or each on a separate bridge, or both not a bridge.
(assume you have the latest firmware).

What you need to do is create an address list in ip firewall rules for all the devices on the 10. network/lan that need to be available.
address list = crossLANaccess - 10.5.17.xx (printer 1)
address list = crossLANaccess - 10.5.17.yy (printer 2)
address list = crossLANaccess - 10.5.17.zz (server 1)
etc..

Then in IP firewall rules in the forwarding chain create a LAN2 to LAN1 accept rule as follows:
/ip firewall
add action=accept chain=forward comment=“LAN2 Access to LAN1 Devices”"
dst-address-list=crossLANaccess in-interface=??? src-address=192.168.88.0/24

Note1: I do not know what interface or interfaces LAN2 is resident on but that is what you put for in-interface (it could be an etherport or it could be a bridge for example).
Note2: Without knowledge of your firewall rules, its a bit of a guess whether this is the way to proceed.
Best to post your config.

If both networks are running from the one single RB2011 in the middle then you do not need to do anything to get them talking. Both networks are connected to a “router” so it will naturally route between them.

Hi Steve, I took it more as he wanted his LAN2 to ONLY be able to access certain devices on LAN1, and after that just have access to the internet.
I further assumed he does not want anyone on LAN1 accessing LAN2 at all.
So, concur there is more info required to understand the scenario but I would add.
The op probably needs firewaall rules in the forward chain.

allow LAN1 to WAN
allow LAN2 to WAN
Allow LAN2 to specific LAN1 devices (as per the rule I constructed above.
Last rule - Drop all Else.

If I was to assume the OP works on an allow everything premise - vice my nothing is allowed unless explicitly stated then it would look like this:

Allow LAN2 to LAN1 (source address list)
Block LAN2 to LAN1 (rest not allowed)
Block LAN1 to LAN2 (if this is also what the OP intended)

My advice is for the OP to provide more clarity and to post their config!