Hi Andrei, thank you for using our forum, my name is Luis I am part of the Small business Support community. In this case I advise you to set a One-to-one rule to translate the IP address, you need to follow the next steps.
STEP 1 Choose Firewall > Advanced Settings > One-to-One NAT.
STEP 2 Click Add.
STEP 3 Enter information in the following fields:
• Private Range Begin—The starting IP address in the private (LAN) IP address.
• Public Range Begin—The starting IP address in the public (WAN) IP address.
• Range Length—Range length maps one to one private address to public address up to the given range.
• Service—Choose the service for which the rule applies.
STEP 4 Click Save.
You can find additional information in the admin guide of your device,
http://www.cisco.com/en/US/docs/routers/csbr/rv180w/administration/guide/rv180w_admin.pdf
I hope you find this answer useful
Greetings,
Luis Arias.
Cisco Network Support Engineer.