Internet disconnected when setting up firewall

[JimPanse]

On my F2-223 i am connected to two different networks via cable ... the first network is connected to the internet ... from both i wanna just allow two IP addresses connecting to my NAS ... therefore i created two firewall rules and picked exactly these two addresses ... However, now it seems the Internet won't work anymore for NAS. If i deactivate both, its working again. What do i have to add to make the NAS internet work again?

Best regards

[TMzethar]

What do you mean by internet IP? Gateway? WAN IP? Please describe the specific manifestation of "the internet no longer works".
Generally speaking, when you only allow these two IPs, internet services from other IPs may not work.

[JimPanse]

Its the gateway address ... my routers IP ... but even with adding it as a third firewall rule, the internet still disconnected ...

With "internet" i mean, the. NAS is not able to do tasks like time synchronization or even downloading apps from the app store.

[Gremlin]

Does each network have it's own router? Do the routers have firewalls?

[JimPanse]

The router has its own firewall ... but this shouldn't matter since for example the app store of the NAS works when i turn off the NAS firewall ... if he router FW would block, it shouldn't also not work when the FW of the NAS is turned off ...

I am a bit confused since i read somewhere, that you cannot block certain routes which are required for the router to work properly ... like appstore etc ...

[Gremlin]

I'm not sure. I was just thinking that router firewalls will normally default to "Deny all inbound/allow all outbound" (So outbound traffic such as NTP would work). However I believe that NAS default is "allow all inbound/allow all outbound". But, as soon as you "allow (some_ip) inbound", the firewall shuts down to "deny everything else". TM have done so much to prevent unintended access, it sort of screws with "normal" thought especially as it is difficult to find the info "under the hood". That, and user permission strangeness.