Hi there,

Today I've switched from ISP.  I use the Deco in router mode. It is configured as DMZ host in the router of my old ISP.  I run a synology NAS at home, which is accessible from the inside of the network as well as on the outside.  This worked fine with my old ISP. 

Today I switched to a new ISP, also made the same configuration. Unfortunately reaching the destination on the 'external hostaddress' internally wasn't possible. Externally everything ran fine.  

Configuration is as folllows: 

ROUTER - DECO M9 - NAS

The router makes DHCP leases in the 192.168.1.xxx series. The Deco M9 is set to 192.168.68.xxx. Of course the Deco M9 has a static DHCP lease on the router, and is set as DMZ host.

After getting a tip from another forum I started looking at 'NAT loopback' and found several topics on this forum handling this problem. I've tried the following points;

1. Disabling Trendmicro security

2. Setting the QOS settings to standard

3. Emptying the high priority list in deco. 

Note: it was working on my previous ISP, with the same configuration (of course the router of the ISP is different). 

To rule out whether it is a problem of the router of my ISP, I connected the Synology directly to the router of the ISP. And all of a sudden the synology was reachable from within my own network (even a client on the Deco M9 wireless network). 

How can I get this back working with the Deco M9? 

Thanks in advance!