unreliable internet connection

[#1]

My recently-installed Plusnet router is failing to connect to certain websites. Examples are Microsoft App store and failing to switch on Norton Internet Security VPN.  I am able to connect normally to (e.g.) my email account, my bank account and lots of others, but when I try to connect to certain sites I see the message "you need to be connected to the internet to access this service", but on every occasion I am connected.  Can anyone please suggest the most likely reason for this problem and what I can do to correct it?

PeterS2

[#2]

@PeterS2 Welcome to the forums. Is this on mobile devices or desktop/laptop?

[#3]

Thank you, John.  It's on my Samsung laptop machine.

Peter

[#4]

@PeterS2 I don't understand that, to be honest - if you can connect to most sites with no problem, something must be blocking the ones you can't access. I assume you are not trying to connect  over a VPN when you get this message, although if you say you cannot connect to the NIS VPN, then I suppose you aren't.

Just grasping at straws, but is this over an ethernet or wireless connection?

[#5]

Thanks, John

I'm using a wireless connection to the internet, through my new Plusnet router that I've only received and set up quite recently.

Peter

[#6]

Can you try over an Ethernet connection?

[#7]

I don't know, John, but I'll give it a try and see what happens.

Peter

[#8]

Let us know the results @PeterS2