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Strange WiFi Behaviour

First Timer
Private Message TalkTalk
Message 5 of 5

Hello all. 

We were upgraded to full fibre sometime last year.


We have a Sagecom Fast 5364-3.T8. We also have a small black box attached to the wall with 4 green lights on it (The Ethernet light blinks fast at all times). The small black box was installed when we had the full fibre put in. 


Since then we have had some strange problems. In general the internet works fine. However, our iPhones struggle with the WiFi now. And by that I mean if we go onto WhatsApp whilst connected to the WiFi it says ‘connecting’ constantly at the top so we have to switch to mobile and it works fine. 

Sometimes we drop out of Teams meetings on work laptops and the desktop but if we switch to a mobile connection it’s fine. 

Playing games and watching Netflix on the TV etc. seems to work fine without issue. 

Every now and then Alexa won’t connect and she needs to be reset to work, but then she does. 

So it’s not a case of ‘the internet doesn’t work’, as it does. It just has annoying intermittent issues. We didn’t have these issues prior to the full fibre and the router hasn’t changed. Do we need a new router? 

I have faulted this to TalkTalk a few weeks ago and they did a check, I reset the router etc. and all seemed to be okay. However the intermittent problem remains. 

Is there any settings I can change or am I able to order a new router to resolve this issue? 

Thanks all


Message 1 of 5

Could you first of all switch the router and ONT off and leave them off for 30 minutes, then switch them back on and retest. Please let us know if this resolves the issue





First Timer
Private Message TalkTalk
Message 2 of 5

Thanks for such a speedy reply. I haven’t asked TalkTalk to disable WiFi optimisation but I would like them to. 

I just tested the issue with my iPhone. With the iPhone in my hand connected to WiFi in front of the WiFi box it just says ‘connecting’ on WhatsApp. If I turn it onto mobile network it connects immediately. 


The lights on the WiFi box and the wall box do not change. There is only 1 wired connection which goes into the back of the TV (only because it’s next to the WiFi box). It works fine without issue. 


Support Team
Private Message
Message 3 of 5

Hi Exoknight,


I can see that Keith has kindly offered to help you with this. Could you just let me know which lights are currently on, on the ONT




Community Star
Private Message TalkTalk
Message 4 of 5

The Ethernet light on the ONT (black box attached to wall) is supposed to flash.


It is probably not the router that is the cause of your problems.


Slow speed, intermittent dropouts, breaks in the signal or no signal on some or all devices or no internet access might be caused by Wi-Fi interference from other local networks, which can also lead to a permanent reduction in speed. No ISP can be responsible for your local environment, this is mainly a byproduct of the popularity of Wi-Fi.

However, other factors should be investigated first. When this happens, what are the lights showing on the front of the router? Do you have any wired connections & if so, how do they perform?

Generally speaking, the 2.4GHz band suffers a lot more from interference than the much faster 5GHz band, but the 2.4GHz one can sometimes have a better range, but this all depends on your local area.

Have you had TalkTalk’s Wi-Fi optimisation disabled on your Sagemcom FAST5364/5464 router? When this is enabled, as it is by default, it has the power to override any Wi-Fi configuration changes that I might suggest that you need to make. This will not help rectify this type of problem if Wi-Fi Optimisation is allowed to change my suggested settings. Only TalkTalk can do this for you, you cannot do it yourself. If not, just request they disable this for you in your reply.

In other words, I try to help you optimise your Wi-Fi connection. The next stage involves sending out a guide to you to help you get me some important diagnostic results so that I can analyse them for you and recommend changes to your router configuration to solve them.

I only send this out to people who request it.

I am not employed by TalkTalk, I'm just a customer. If my post has fixed the issue, please set Accept as Solution from the 3 dot menu.
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