TV-BOX doesn't see RT2600ac 5ghz network

[egrassa]

Hello all,
I really dont know what should I start from.
I bought tv-box yundoo y8 with dual-band support (2.4ghz and 5ghz, ac). It worked perfectly with my previous router Linksys EA9500 5ghz net. After switching to Synology RT2600ac it just blinded to see any 5ghz nets.
Furthermore it can connect to router only on 2.4Ghz G standard on 54mbs. It is really disappointing due to I had been choosing new router for a long time between this one and Linksys WRT3200ACM and seems I failed.
I changed regional settings, channels, band formulas, turned on/off smart connect etc...nothing happens. it can only see 2.4.
who can give an advice where i should start for troubleshooting. Or just return it and get Linksys?
Thanks.

[Scott H]

It's possible this is a similar issue as observed with the Belkin Wemo devices in that Smart Wifi needs to be turned off and the network channel width forced to 20 MHz. If on smart wifi the 5GHz channel width defaults to 40MHz.

Worth a try.

[egrassa]

After about 12 hours of investigating I managed to figure out the root cause or actually root causes.
First one mostly related to the firmware of tv-box firmware since it just could see anything else except 2.4ghz, G, 54mps at all.
After it was re-flashed it was be able connect to 2.4G with N-mode 144mps, but 5G was still unreachable.

I haven't mentioned that I checked almost every 5G channel before re-flash and nothing happened.
So the second reason is that in auto mode router selects only 5G 100's channel, always regardless of anything. And this channel is
not supported by TV-box. I switched 5G to 36(40, 44, etc) channel and bingo I got my 5G net is visible))
And that's my story.

[egrassa]

So as my last issue is not router related mostly there are a few questions about auto channel setting for 5Ghz range.
Does regional setting affect to a set of channels which is used for auto assignment?
Does router prefer the channels without DFS for auto assignment or any available channels for the region can be selected as auto?
If it doesn't is it possible to limit set of channel for auto assignment?

[BrianE]

After about 12 hours of investigating I managed to figure out the root cause or actually root causes.
First one mostly related to the firmware of tv-box firmware since it just could see anything else except 2.4ghz, G, 54mps at all.
After it was re-flashed it was be able connect to 2.4G with N-mode 144mps, but 5G was still unreachable.

I haven't mentioned that I checked almost every 5G channel before re-flash and nothing happened.
So the second reason is that in auto mode router selects only 5G 100's channel, always regardless of anything. And this channel is
not supported by TV-box. I switched 5G to 36(40, 44, etc) channel and bingo I got my 5G net is visible))
And that's my story.

My Amazon Fire Tv will only recognise channels 44 and below as well, so "Smart Connect" is a useless feature for me as I can't use it (even without the Fire TV requirement, it would still be of no use as I need to restrict my 2.4GHz channels to 1, 6 or 11 to avoid cross-channel interference).