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FAST5364 firmware SG4K10002816t not sending IPv4 DNS to DHCP devices

Whizz Kid

Whichever DNS option I set ('Obtain DNS Automatically' or 'Manually Specify DNS') in... 

Dashboard > See internet settings > Manage advanced settings > Internet connectivity

...I cannot get any device that connects to the router using DHCP to get usable internet without having to manually set each device's DNS to a static value (such as or or even the local address of the router which for me is


If I set DNS on a Windows 7 pc in IPv4 properties to 'Obtain DNS address automatically' (i.e. if I don't set a static DSN on the computer itself so am relying on one coming from the router) then ipconfig /all shows no IPv4 DNS, it only shows 3 values which perhaps are IPv6 addresses... 

DNS Servers . . . . . . . . . . . : fec0:0:0:ffff::1%1

...whereas if I set the Windows button for 'Use the following DNS server addresses' and one of the addresses or etc then browsing works and ipconfig says...

DNS Servers . . . . . . . . . . . :

(or or whatever I set, in the IPv4 network properties via Windows Control Panel)


In the past I used to set a static DNS address for the router to send out, in...

See internet settings -> Manage advanced settings -> TalkTalk Wi-fi Hub -> DNS -> Enabled ON

...but that option now seems to be greyed out and unchangeable (I've seen in other incidents that it is considered inefficient, although now I realise I would want the router to work as if I'd put there, which surely ought to be the same behaviour one would expect with Enabled OFF


How do I get the router to actually tell Windows7 (& all the other DHCP devices) a valid IPv4 DNS address (either it's own or the one specified in Internet connectivity) ?

Whizz Kid

BTW, the reason I used to set a static external DNS address such as (or more recently for the router to send out to DHCP devices, was that I found the DNS server within the router to be unreliable - after a few days or weeks it would stop working, as if some internal table or cache had overflowed or become corrupted (possibly in the way that used to happen due to virus attacks on some older routers).  Bearing this in mind it seems the greying-out of that option makes the Sagecom FAST router less robust - they have removed the failsafe option for bypassing the builtin DNS server.  Not good.

Whizz Kid

Today I seem to be able to set Enabled ON, so the router sends out a specific DNS server address like it used to months ago (I've set it to the router's) which makes DHCP connections  work properly, whereas yesterday I could not do that, it was greyed out. 

See internet settings -> Manage advanced settings -> TalkTalk Wi-fi Hub -> DNS -> Enabled ON
Primary DNS Server

The underlying problem, no usable DNS is received by DHCP devices if Enabled is OFF, still exists.

What changed?? (the firmware level didn't) 

Whizz Kid

And today I am again able to change the 'Static DNS Server Configuration', it is not greyed out!

I've worked out what's happening - you can only change the static config (ON/OFF & the 2 addresses) at...
See internet settings -> Manage advanced settings -> TalkTalk Wi-fi Hub -> DNS

...if this other setting at... 
Dashboard > See internet settings > Manage advanced settings > Internet connectivity set to 'Obtain DNS Automatically' !


But why? They're shouldn't be related, one is what to send to DHCP clients and the other is what the router will use to accumulate entries in its DSN server, which independently may or may not be what the DHCP clients are told to use.  So there should be no reason to greyout one of them depending on the setting of the other.  Madness!!  What are the people who maintain the firmware thinking of? 

But anyway, you can circumvent the restriction by setting the Static ON/OFF etc before setting 'Manually Specify DNS' if that's what you want (only really matters if you want the router to obtain its own requests from non-talktalk dns since the 'Manually' address would only effect those, unless you'd had to set the ON to force the router to tell DHCP clients its own IPv4 address, which it didn't seem to do otherwise, see original problem description).


I see there's a later router now, the 'Black' one.  I wonder if the firmware & gui in that is better - Sagecom's FAST5364 has seemed a bit quirky ever since the trial, too many levels of menu and too much having to go back to the top dashboard - only just useable compared to the older DLink devices which always kept the main menu visible at the left.