Source address for Updates and NTP

Hi There

My Rb750 is setup as a NAT Router/Firewall with PPPoe to an ADSL modem. I’m having issues with the RB750 device itself fetching updates and contacting external NTP servers. It looks like it is using the public WAN IP address as source when connecting externally, even for just a ping. Is there a way to make it use an particular internal interface address as the source for external communication? I’ve tried numerous combinations of firewall and NAT rules to get it working as is but with no luck. I can see the packets leaving but nothing coming back. Everything else is working fine.

Thanks for any help

Have you tried using 1:1 NAT?