"This site can't be reached"

[njf]

So I’m hoping there’s an IT/network expert here who can suggest a solution as BT seem completely stumped! Sorry for long post but I think people may assume it’s something simple which we haven’t tried.

My elderly parents have been having issues for about six weeks now with seemingly random websites not loading on both their Windows 11 PCs saying "This site can't be reached".

Sounds not too serious but my mum is 88 & does all their shopping for food etc online. Some examples are Amazon works, eBay doesn’t. Tesco & Sainsbury’s don’t work, Waitrose does. They can’t access their bank accounts but email works perfectly. I was there last week & googling BT shows results but the main BT website won’t load!

They’ve had three engineers out to them & I've spoken to BT Guides at least half a dozen times but nobody can suggest a solution.

I've tried everything I can think of:

- tried multiple browsers - cleared browser caches - changed to google DNS - disabled firewall & anti virus - disabled Ethernet & connected by WiFi - restarted router - factory reset router - even bought a new PC for my mum which worked perfectly at my house but not at hers!

Where it gets weird is some days everything’s fine, then suddenly lots of websites are unreachable. Even weirder I’ve been there using my iPad on their WiFi & all sites are accessible even when they’re not on either of their PCs!

Something appears to be making some websites so slow to load they display "This site can't be reached”. I think it must be something at the upstream network but nobody has any idea what’s causing it or how to solve it 😞

Any new ideas welcome as BT appear to be at a loss.

[rbz5416]

Might be worth checking for malware given that the iPad works OK, as did the new PC. Do they have Norton running on their PCs? If not then see if you can install that through BT.

As a backup, download Malwarebytes to a USB stick to take with you, in case  you can't get Norton to install.

[njf]

Thanks but I don't think that's the issue. 

To clarify I installed Windows 11 from scratch on the new PC. Working perfectly at home, took it to my parents house & immediately had issues accessing websites. 

The iPad thing is very odd as no issues on that while PC didn't work on ethernet or wifi. The iPad doesn't have a Sim card so same wifi.

It's been fine for last six days so I assumed BT had done something but yesterday suddenly couldn't access many websites again 😡

[njf]

So after both PCs  suddenly working perfectly for 6 days it suddenly went back to how it was before, not able to access many websites.

BT had sent a new router in the meantime so swapped that and that fixed the issue for a whole 3 days but now has same problem as before.

Anyone ever had this? Both BT and I have run out of ideas except maybe changing supplier?

[Leanne_T]

Hi there @njf 

I am sorry this has started to happen again after working perfectly. 

I would suggest getting back in touch with our broadband tech team to see what else can be suggested for you to get this sorted. 

Please keep us updated. 

Thanks. 

Leanne. 

[countrypaul]

Could the Windows 11 machines have MAC randomisation turned on? If so then after a few sessions all the IP addresses could become used with no fresh ones to issue until a DHCP lease runs out. A new router would work for a while, as would a router reset, the iPad might work if it got an available address and was not using MAC randomisation (or whatever Apple call it).

[Emrsw01]

I've got a very similar problem. Can't access some sites using my broadband from Windows 11 pc connected by ethernet or my mobile or tablet using Android. If I use a Vpn to UK server on either I can connect OK. Also if I connect using mobile data on my mobile it connects OK. Happens with 4 different browsers and with anti virus disabled. Also happens on some apps.

One site which always fails is www.topcashback.co.uk and the TopCashback Android app. Again it is OK using a vpn or using mobile data.

Tried changing dns but can't get to the reason. Would appreciate any help on this one. 

[Irish-Lynda]

you may have to google how to do this as I cant remember at the moment

but, on your computer there is a 'properties' tab to do with your internet connection, this is the tab that allows you to make changes and shows you IP address etc, 

on my PC (win 11) it is settings - network and internet - advanced network settings 

click on your internet connection (wireless in my case) - view additional properties

and you will see a IP address for DNS servers, try and change them to another provider, such as google (8.8.8.8 and 8.8.4.4 ) and see if that makes a difference.

You will need to google a bit as I can't work out how to make the change, but you can

[Emrsw01]

Finally got this resolved by starting a new thread and it was suggested i may have BT web protect enabled. I did althogh didnt realise. I removed it via My Bt. I then had to reboot router and all was then fine.