FYI : IPv6 Prevented VPN Connection

[Anvil_Iron]

My wife uses VPN for work and one day she wasn't able to connect. I checked the router (Zyxel NR5103E) web-config and noticed the Primary/Secondary DNSv6 server addresses info were present which weren't before.

I tried disabling IPv6 in the WAN and LAN settings but internet service stopped.

I then enabled manual APN mode and changed from 3internet to Three.co.uk and restarted the router. After restart, the IPv6 info was N/A and the VPN was able to connect. VPN also connected when APN was set to 3internet with manual APN enabled.

The strange thing was when APN Manual Mode was disabled and router reset, IPv6 info was displayed. It looks like the router was obtaining IPv6 and IPv4 info from Three if manual APN mode is disabled. This could be the PDP Type being set to IPv4/IPv6 automatically by Three where as in manual APN mode, I have it set to IPv4 only.

[Cymbalhead]

Actually, I take it back, I've just done another speed test and it's over 300mbps. So maybe that isn't going to be a problem.

Still extremely frustrating that this has happened though. Inexplicably various devices stopped working or displayed very very weird behaviour (the BT whole home mini discs had a red light that stated they were not connected to the internet yet somehow were still able to provide access to devices connected to them).

[HampshireBaz]

Have been having issues with my three 5G CPE MC801 over the past few days and have just changed the APN three.co.uk and now I have my Internet back!  Three telephone support didn't help.  Thanks for posting.

[Amiraj]

I have had the same issue but as soon as I change the APN settings as instructed here to manual I lose Internet and none of the devices can connect, changing it back to Automatic and I can atleast connect with my phone and laptop. Ring doorbell, TV and my wired Tp-Link extender don't work.

[cruisealtitude]

Thanks for this. This worked for me. My television and Honeywell smart thermostat stopped working all of a sudden, and changing the APN worked for me, changing the domain from 3internet to three.co.uk.

Thank you!

[456]

Something needs to be done about this. I've had nothing but problems ever since I renewed my contract at the end of last year. Months and months of hassle. @JonathanB 

[Storm-14]

Just wanted to say thank you. This issue started out if nowhere the other day. After months of playing ps5 just fine. Following your steps solved the problem when nothing els did. Your a legend 

[456]

What changes did you make and did they affect your download speeds?

[SerenaJoy]

Same issue here - suddenly stopped being able to connect on Sunday, using Cisco AnyConnect. Other half is using Forticlient VPN with no issues. I’ve logged into the router using default password and although I can see advanced settings I don’t seem to have the same options as others on this thread - no option to switch APN to manual. Any help appreciated, working from home has been virtually impossible all week

[456]

Can SOMEONE from Three respond and sort this out? Issues for almost ONE YEAR NOW. 😢 @JonathanB 

[BJ292]

Thanks for this.  Worked a treat to get my Blink camera working again.