CrowdSupport®
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Level 2: Rookie

NBN is Blocking OpenVPN on IPV6

I have a Telstra GatewayMax modem connected to NBN HFC with Sim mobile backup.

My computer gets assigned IPV6 address fine.

 

I spent days trying everything to setup OpenVPN connection using IPV6 UDP Port 1194. There is no way I can get it to connect over NBN. If I connect to my Mobile phone WiFi hotspot, it connects fine. If I unplug NBN connection to the Telstra router and fail to mobile broadband, it connects fine.

Reconnect NBN, and it will not connect. I have proven without doubt that NBN is blocking the connection, while Telstra's mobile broadband does not block it.

Why is this so?

Can it be fixed?

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9 REPLIES 9
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Level 24: Supreme Being
Level 24: Supreme Being

Re: NBN is Blocking OpenVPN on IPV6

What model modem and what firmware does the modem have installed on it? This information is on LHS of modem's log in screen.

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Level 2: Rookie

Re: NBN is Blocking OpenVPN on IPV6

Technically it is a gateway/router and not modem, as it is connected via ethernet to the NBN cable modem. I hate that Telstra refer to it as a Smart modem.

Model : Arcadyan LH1000

Frimware:0.09.11r

I believe the gateway is working correctly as on mobile connection it works correctly.

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Level 24: Supreme Being
Level 24: Supreme Being

Re: NBN is Blocking OpenVPN on IPV6

When in backup mode Telstra Broadband protect is bypassed. When on the normal connection broadband protect might be blocking the VPN site. Telstra broadband protect can be bypassed by changing the both IPv4 and IPv6 DNS in the modem. (Go to Advanced > Local Network). Disconnect and reconnect PC for settings to take effect.

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Level 2: Rookie

Re: NBN is Blocking OpenVPN on IPV6

That is not it.

I thought you might be onto something, but I tried google and opendns for both IPV4 and 6. Each time I tested it did not work until I disconnected NBN and failed to 4G backup. 4G works fine.

Maybe some bad routing on NBN. My VPN server is running on a laptop on Telstra 4G, so possibly direct IPV6 path works well because of that.

There must be a simple way around it.

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Level 24: Supreme Being
Level 24: Supreme Being

Re: NBN is Blocking OpenVPN on IPV6

When on $G the modem only has a IPv6 IP address on the WAN. When on the main link the modem has both an IPv6 and IPv4 address. You could try disabling IPv4 on the laptops network adapter to force the use of the modem's WAN IPv6 address.

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Level 2: Rookie

Re: NBN is Blocking OpenVPN on IPV6

Good idea. I tried it but no change.

I changed the LTE to IPV4V6 when I got NBN and realised IPV4 web sites did not work if NBN went down which was frequent at first. Stupid that is not the default.

Also IPV6 seems to be working when I go to ipv6-test.com.

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Level 24: Supreme Being
Level 24: Supreme Being

Re: NBN is Blocking OpenVPN on IPV6

The only other thing I can suggest is to disconnect Telstra modem and connect the laptop directly to the NBN NTD and check if VPN works. If it doesn't work then it is definitely the NBN link causing the problem and will not be able to be fixed by changing any modem settings. If it does work then a setting in the modem is causing the problem.

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Level 2: Rookie

Re: NBN is Blocking OpenVPN on IPV6

I tried connecting direct to NBN modem and same result as I expected.

The Telstra Gateway is working fine. NBN is blocking the path. 

 

I don't understand why NBN would be blocking OpenVPN on IPV6 specifically as IPV6 works for other things. I also have OpenVPN working on IPV4.

Possibly the government cannot spy on it because it is direct PC to PC without any port forwarding required.

 

This should be the simplest way to connect securely to a remote network, and they are making it impossible.

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Level 1: Cadet

Re: NBN is Blocking OpenVPN on IPV6

It's not NBN, it's the Telstra gateway - I have the same gateway (LH1000), but I haven't been using it until recently (for troubleshooting due to some dropout issues). Had a site-to-site OpenVPN working fine with my old router, now the Telstra gateway won't let it connect over port 1194. Changed port to random high port, and it's back up and working. Once my connection is stable again, the Telstra router is going back in the box again!

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