Extender and my network? Take a Look and Help!

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[wireless]

Please any advice would be great.
What I am working with
Fiber 150 to telus router (T1200) ->
cat5 Running outside to switch upstairs (provided by Telus) ->
From Switch
ethernet to extender actiontec6000 ->
ethernet to Netduma router->
From Netduma
ethernet to gaming console
ethernt to computer

Here is the issue,
i have port forwarding on first router
when I enable it t Netduma works
when I disable it extender works
Why?
it wasn't always like this. It was working ok before then nothing. Telus support tells me to disable port forwarding but I should be able to run this setup...what am I missing?
Any networking help would be appreciated, new to all of this so kinda at a loss.

Thanks
R




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