I had a similar (not same) call and we found the router firmware was the problem. Yes we had to swap out the router to nail it but the router maker did roll out firmware so it's working fine now.
Hope it's that.
I have Dlink 868L router and 2 Windows PC, NAS, Android TV are wired connected.
I have AS-604T NAS since 2014 and has been working fine. But for last 3-4 month it is behaving weird. It is on auto power-off and power-on mode.
• Power off at 2am at night
• Power on at 5pm
Each time it is turn off at 2am, it kills the internet and whole network connection (Yellow triangle on Windows PC). In the morning when I get up, there is no internet (wired and wireless).
Each time it turn on at 5pm, it kills the internet and whole network connection (Yellow triangle on Windows PC).
When I try to switch off and switch on manually, then also it kills the internet/network.
To get back the internet, I need to power cycle the router.
I tried using port Lan2 and also changed the cat5e, without any success.
On further trouble shooting, I notice that if I pull out the TV ethernet cable from rounter, the connection comes back. The connections stays even after inserting the TV lan cable back in router.
Please help me if fixing this issue. It is very frustrating.
Thanks in advance.

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