Networking issue - Firestick

[#1]

As the broadband modem and router connecting to PN on the 2nd floor, I have a Talktalk D-Link DSL-3780. This also provides wifi access. This has a wired LAN connection to a Netgear DG834G on the ground floor, in the living room, just as a wifi AP. (wifi Access Point) DHCP is enabled on the 3780, disabled on the 834.

The Firestick works fine in the bedroom, using the 3780's AP, but when testing it on the living room TV, using the 834's AP, the streaming breaks up/ it constantly complaining it has lost internet access. I have tested an alternative LAN cable, so its not that.

I have tried two other Netgear routers with AP's in place of the 834, with exactly the same result. I have also tried resetting them to factory settings and reconfiguring from scratch with the same result.

I can successfully stream video/ use Youtube on my laptop via the 834. 

I do sometimes have difficulties accessing the last mentioned items and sometimes other things on the internet, but not often. When I do have trouble, often I will find I cannot log into the 3780 - it rejects my password. If I then reboot the 3780 I can log in and all but the Firestick works fine.

I also have a Samknows white box, between the 3780 and the rest of my wired LAN. I have tested things without that and it made no difference. 

Anyone know what might be going wrong please?

[#2]

Am I using the correct setting here please...

I am using the one marked with *********************

Security Options

Disable

WEP (Wired Equivalent Privacy)

WPA-PSK (Wi-Fi Protected Access Pre-Shared Key)

WPA2-PSK(Wi-Fi Protected Access 2 with Pre-Shared Key)

WPA-PSK+WPA2-PSK *********************************************

WPA-802.1x

WPA2-802.1x

WPA-802.1x+WPA2-802.1x

[#3]

Any one of the PSK ones is correct. WPA 2 version is the most secure from a security aspect.

[#4]

The Firestick suddenly started to work yesterday afternoon with both routers configured as they were..

I am still suffering the occasional disconnection though..

[#5]

Did the Fire OS update or something around that time? Settings->Device->About, if you didn't know where to look.

[#6]

It has twice announced that it has updated, in the week we have had it, but it seemed to connect fine to the ground floor AP, but then struggled to get data through the modem/ AP connected to the broadband. I was also having trouble logging in to the latter, on my laptop connected to the ground floor AP. It just kept popping up login box, me filling in the correct details and repeatedly popping up the same box. The only way out of the loop, was to reboot it. 

At the moment it is working quite well.