I have the Sagemcom FAST 5364 router. I have recently needed to increase the reach of the wifi. I initially set up a DEVOLO powerline with wifi access point that I already had. This worked ok but every few days the router dropped the internet connection so I had to keep rebooting it. So I purchased a Netgear EX7700 Nighthawk X6 extender. This has worked ok, but today, my wife's laptop couldn't connect (couldn't get an ip adress from DHCP); again the router had to be rebooted. The firmware on the router is SG4K10002816t. Could a firmware upgrade fix this problem?
You are on the latest firmware. How does this extender connect back to the router, via a powerline, cable or the router's WiFi? Have you had WiFi optimisation disable on the router by TalkTalk?
In that case, it is not an extender, it is a repeater. As a generic statement, they are not always very satisfactory. This is because if they use the same WiFi channel as the router & most do, they broadcast this signal out in all directions, including back to the router. When it does that it is very likely to cancel out the router's WiFi and then you have no connection to the router.
WiFi optimisation is a remote management utility of TalkTalk's which has the ability to override any WiFi configuration changes made on the router.
I can try to see if it is possible to do anything with the WiFi reception in your property if you want me to, but not until TalkTalk have disabled this facility. Otherwise, any changes I suggest that you make to the router, WiFi Optimisation is very likely to undo.
An update - After some further investigation I have now determined that it is just Chromebooks that won't connect, having this DHCP issue. Other devices connect without an issue. So I have now also raised the problem with the Chromebook Community and with Netgear support. My concern is that the three companies involved here will just blame each other!
I have also now decided to give the extended wifi a separate, distinct SSID (although the problem still remains). As you say, the extended wifi is currently using the same channel as the router (channel 6) and it isn't possible to change it. I don't know whether this is a coincidence or whether the extender sets itself up to match the router's channel. I have asked Netgear and I await a response. I don't actually understand why the extender would use the same channel as the router - as you say it could cause interference! If it does automatically match the router's channel then I guess that there would be nothing to be gained in asking TalkTalk to disable optimisation.
That is the way repeaters work, they just clone the WiFi settings of the router, normally via WPS.