For the life of me I cannot figure this out other than to assume there is a hardware problem.
2.4 GHz works fine
5.0 GHz connected no data tranferred
Tried different channels on my router
VPN on & off
Other devices work fine
Router & Firestick about 1’ apart
Rebooted everything
What do you all think?
Are you sure the router actually has the 5GHz band enabled?
Yeah…other devices are running off it. Forgot networks and reconnected several times on the FS.
Hey @Money You’ve got a tuff one there…looks like your troubleshooting is pretty thorough. I’ve got 2 questions for ya…is your 4K still within the refund/replace range? & is the “5.0 GHz connected no data transferred” something you just wrote to explain or is that the warning your firestick itself showed when going into settings/network & clicking on your home network?
Does your router have wifi6 (AX)? if so try disabling it and check. Might need a reboot.
Unfortunately, not able to return it. That was my observation. It says connected. I do a speed test and no mbs transferred up or down. Not able to stream content. 2.4 Ghz works great though 
No Wifi 6 on my router 
what type router? Asus routers have “smart connect” which combines 2 and 5 for just one and it uses the best one
So your 5GHz network shows on your firestick and it’s logged into that? Very odd issue.
It is a D-Link smart router. Optimum cable. Broadcasts both bands to connect to. 2.4 Ghz & 5 Ghz…
Oh well…Maybe has something to do with the actual gateway (modem).
Thanks for all the input…appreciated…
I know it has both the 2.4 and 5GHz band, but my question is, have you chosen the 5GHz SSID on the firestick, entered your password and signed in?
Yeah…I sign in and it connects to 5 Ghz but no upstream or downstream data is transmitted. Works fine when using the 2.4 Ghz channel.
Thank you. That helps. Now you will need to make sure that on your modem the 5GHz band is broadcasting on channels 149-156 or 36-48.
what does it show when u click on settings/network/your network?q
Did a complete reset of The Firestick 4K so it is factory fresh?
Strange problem.
Sure is an odd problem…says connected…security…WPA2 PSK…no connection problems…tried all the FS friendly bands…149-156 or 36-48…
Call Amazan customer service for tech help.
starting to think faulty chip
Me too…that’s why I asked him what his fstick network was showing for channel, band & connection. The wifi adapter may not be receiving on the 5.0 band. He said all other devices were working on the dual bands…so that “should” take the router out of the equation & put the 
on the firestick.
Yeah…has to be some hardware within the FS itself…thanks for all the input everyone…I initially thought so, but thought hey… throw it out there and see what ya’ll were thinking.
Well…it still works, just not to its full potential…so it’s not totally broken. I looked around the web for similar problems but came up with nada. Some of us have been trying out the $20 ONN android boxes from WallyWorld & they’ve been working pretty well by most accounts…maybe a bit of a remote problem with a few…but pretty good for a $20 device…in the event you’re looking for a replacement/backup. 