R6400v2 Port Forward not working

I'm trying to forward two ports from the WAN, one port each to two different hosts in my home. I'm doing this with the routers port forwarding configuration.

In the section Advanced > Administration > Advanced Setup > Port Forwarding / Port Triggering

• External port 25 routes to internal port 25 on local machine 192.168.1.10
• External port 9000 routes to internal port 9000 on local machine 192.168.1.11

I looked through all of the settings on the admin pages via 192.168.1.1 and found a couple things that look like they might be able to open or block ports.

• I set "Respond to Ping on Internet Port" and now ping responds from the WAN side of things.
• I set "Disable Port Scan and DoS Protection", thinking that would allow responses to port scans.
• I have service blocking set to "Never".

Is there anything else in the router config which could block ports from passing through and getting forwarded?

Thanks much!