Amazon Fire Stick on 5ghz changing channel

[Wizard7070]

I have split 2.4 and 5ghz SSID as I live in a block of flats and other blocks near by I find 2.4 to be slow and lots of buffering assuming due to interference so use the 5ghz which is fine and no problems. 

whenever the router reset I did have to change the 5ghz channel as Amazon fire sticks only pick up the 5ghz on channel 36 or 48 but defaulted to higher. Problem I have now is I can no longer change channels and talking to Vodafone no longer option and stuck on my fire sticks on 2.4

has anyone got any tips how to get around this or improve the 2.4 with so many SSID broadcast around me. Other settings to try?  Do 3rd party routers still allow changing channels? 

[CrimsonLiar]

If the FireStick is in the same room as the router, then I don't think there is much you are going to be able to do other than talk to customer services to see if they can fix the 5GHz to a low channel.  If the router is not in the same room, then a powerline (not av2000 it'd probably interfere) to WiFi access point placed near the FireStick might help.  It's only a may help, because if you are on FTTC in a flat there is the possibility that your phone line and powerlines run parallel to each other again potentially causing interference.  *Oddly if you do this, then you sometimes get better results if you can knock down the 2.4GHz transmit power a notch or two.