My previous CISCO router (from my ISP) has been changed to Bridged mode, because I wanted to use mine (Synology). Afterwards the internet connection and the subnet worked fine, but my (DDNS) FQDN (from NO-IP.com) got resolved wrongly:
Desired scenario (also on the subnet)
the FQDN gets resolved to an external IP address every time instead 88.1.2.3 of the internal 192.168.1.x
Port Forwarding: from 9900 to internal 192.168.1.100:80, from 9990 to internal 192.168.1.101:80
Current state:
if I try to reach the FQDN from the subnet it gets resolved to an internal one 192.168.1.x
both the request to myfqdn.ddns.net:9900 AND the request myfqdn.ddns.net:9990 gets routed to 192.168.1.100:80
Trials:
- I experimented with several DNS settings on the router (without deep understanding), it did not get better.
- I tried to reach my servers (NAS) from outside, it works like a charm.
Remarks: one of the devices defined in the Port Triggering rules is a QNAP NAS, which had a UPnP activated at the beginning (now turned off); at that time there has been such mysteries.
