Hello
First of all… sorry for my Bad English.
I have 2 Networks NOT Bridged, No Routing… (4.th & 5.th Floor)
Net A 10.10.10.xxx & Net B 192.168.1.xxx
In Net A i Have a NAS with WEB Server & WiKi (10.10.10.10 port 80)
In Net B is a User who need access to the Wiki on the NAS.
I dont have Access to the Routers of every floor only to switches
I think i use a RB750 and configure a Static NAT ? Or how can i solve this ?
Thank you very much for Help
You can make a virtual appearance of the NAS on the 192.168.1.X network - e.g. 192.168.1.2 = “the NAS”
Add the “nas” IP to the P5 interface of the RB750 as a second IP address (the primary one is for communicating with the 750 itself)
Then dst-nat this second address to 10.10.10.10:
/ip firewall nat add chain=dstnat dst-address=192.168.1.2 action=dst-nat to-address=10.10.10.10
Meanwhile, on the 10.10.10.x network, choose an available IP address in that network (probably even a dhcp-assigned address would be fine).
Then make a srcnat rule:
/ip firewall nat add chain=srcnat out-interface=ether1 action=masquerade
This will give the many-to-one, one-way connection you want. The NAS will see any access from the LAN B as if it were the P1 IP of the RB750.
The users in LAN B should just use the IP 192.168.1.2 to reach the NAS.
Thank you so much… 
(youre my Lifesaver…)