Telegram being blocked

The Virgin Media DNS blocks some Social media / Messenger / Conf call / Wi-Fi Calling applications when "Child Safe" is Enabled in the Virgin Media online account.  Perhaps see if this needs to be Disabled & retry.

"Child Safe" is a DNS content filter, so it is easy to bypass by modifying your device to use OpenDNS or Google DNS i.e. a Public DNS that is not filtering 18+ content.

Unless VM are blocking then likely  routing issue

The Telegram app for Android is working for me via a VM Hub in Router mode & using the VM DNS.

Yes - getting exactly the same with Telegram. Stopped connecting yesterday evening. Connects if I switch from Broadband to connection via mobile.

Same thing is happening to me

I have no child settings on 

I've been on the phone to them and have a 5.x hub, they seem to think its my router, it damn well isn't. the issue is outside of my home network but the CS agent doesn't believe that, saying that people aren't reporting it, well community forum and twitter seem to show different.

Same here. Started the evening of Friday March 1st. Spent an hour and half on the phone with their dreadful customer services on Saturday (once I'd finally managed to get through to an actual human, which seemed damned-near impossible), just to be passed from pillar to post, only to be told by some idiot who clearly doesn't know what he's talking about that it is "impossible" for Virgin to be blocking Telegram and it must be a problem with the app(!).

However, it's clearly a problem with the Virgin connection as it affects all devices connected to the Virgin connection, but on mobile data it's fine. If I connect a different router with a different internet connection (I'm a new customer so I happen to have my old router still active) into my mesh instead of the Virgin one, then everything works fine. And if, like you, I set up a VPN to bypass blocking done by Virgin then it also works fine.

The only thing the useless customer support person did after an hour and a half was to switch child safety and web safety settings off, which I had already done and which didn't help.
 

Child Safe has a nasty habit of affecting connections (blocking office VPNs) even when it appears to be disabled,
did you try using a Public DNS so as to be quite sure Child Safe was totally bypassed ?

Something is definitely wrong on their end. Using a VPN it's possible to bypass this block but not everyone wishes to, or can use this option I've not yet tried a public DNS but that will be next. I'll let you know how it goes..

I've not seen any Telegram issues, our configuration is a Hub 3 in router mode all very standard.