Use WAN or LAN Port ?

In your situatuation, these considerations should apply:

The Draytek 2950 is the primary router -

All of your Apple routers are just equal devices receiving internet and network info from the Draytek because they are all attached via ethernet.

In the Airport Utility, their configurations should all be in "bridge mode", "connected via ethernet" to their WAN port (this leaves the LAN ports to be used for other devices such as your Roku).

To just be an access point, the wireless mode would be "off". To provide wi-fi you would "create a wireless network" with the same name, password and type of security as your primary network and "allow this network to be extended".

Leave all other settings at default.

The diagrams generated by different Airport Utilities might be slightly different. This is not a problem. In your situation, all connecting lines should be solid.

Please note that when connecting any Apple device via ethernet, the WAN port is always the internet or network "in" port. The LAN ports are always LAN ports. If the Express or Extreme or Time Capsule is used as a wireless extender or wireless access point as opposed to via ethernet, then all of the ports become LAN ports.

I know this can be confusing. If any of the gurus read this, they might have some clarifications or suggestions that I have not covered.

Yes - and if the Airports are all directly connected to your Draytek you will get the tree diagram - if you use switches or powerline adapters it could switch to an inline diagram - and btw, I have a Roku 3 in my network and it works very well with my Airport devices (I have an Extreme a/c running the show) - and everything in my network is also attached via ethernet.

I understand that you would like to know why things work or don't work the way they do - I am the same way - but sometimes they try and fool you and they put the battery in the boot (ha ha) - Apple works and plays well (most of the time) with other Apple products - most of the technology is proprietary so that is logical - however Apple also tries to be compatible with other manufacturers' products - they do a good job but total compatibility is impossible -

So referring to your question on the diagram:

You have a none Apple router which is also a switch.

It is providing DHCP and NAT to all of your devices so your Apple devices are just another peripheral.

You also have a Wi-Fi network to deal with.

Therefore the Apple Utility whether it is on your Mac or iPhone cannot always interpret the proper routing sequence - it is literally gets confused - if you had all Apple products directly connected, the diagram would be consistent and btw there is no documentation on this - I learned it by trial and error.

And you may have already done this but whenever you make multiple changes, you should reboot the entire system starting with the modem by shutting everything down and power up up each segment down the line - and remember that if the modem has a battery, to remove and replace it before you start.

Here is link to a network diagram from Apple - it is not exactly the same as yours but you will get the idea:

http://support.apple.com/kb/HT4260

There is other information at Apple support - choose "all products" then choose "wireless" then "Airport and Time Capsule" - the articles there should anser most of your questions.

Regards,

Charlie