VPN Ports

[#1]

I just moved to PN from Sky using the same router.  I had a L2TP VPN server set up and working on my Synology NAS to allow access to my home network externally.
However, it looks as though the L2TP VPN ports 500, 1701 and 4500 are blocked by PN (I tested the ports on http://www.yougetsignal.com/tools/open-ports/ - see attached), even though the firewall on my PN dashboard is off. 
If the firewall is completely off, why is the VPN routing not working?  Nothing on the router has changed other than the connection settings.
This is not really acceptable to me.
Thanks in advance.
 

[#2]

PN do not block the ports used by L2TP - I had a working L2TP VPN server (running on my router) when I was a customer.
Have you disconnected and reconnected your router since turning the PN firewall off? 

[#3]

Yes, I have.  Quite a few times.  The ports are blocked/closed as can be seen in the open ports tool snapshot.  I have other ports open for IP cameras and they get reported as open.  It's just that the VPN used for VPN that are reported as closed.  I've yet to see if I can VPN to work the other way on the new connection.
Should I contact PN's Traffic Management department?
adie:quote

[#4]

@pwatson
I have only ever rebooted the router.  Should I have rebooted the modem? Thanks

[#5]

Does your router have a firewall log? I can think of no reason why these ports would be blocked. Am I right to assume it's TCP and not UDP traffic you're trying to forward?

[#6]

Quote from: Bob

Does your router have a firewall log? I can think of no reason why these ports would be blocked. Am I right to assume it's TCP and not UDP traffic you're trying to forward?

I forward both TCP and UDP traffic.
Yes I've looked at the firewall log but there's nothing listed as traffic doesn't reach the router!
When I try connecting with a client the response is that the server is not responding.
What next?
Thanks

[#7]

It's definitely possible:

Quote from: Nobody

... even though the firewall on my PN dashboard is off.

Looks like it's set to 'low' to me, rather than being switched off?

[#8]

Is that my line? I know it should be possible but at the moment it's not reaching my router.  I switched the firewall from off to low as the help text says that low is the only possible option that works for VPN. 

[#9]

No, it's one of my lines at home. I started an FTP server on port 1701 and created a port forwarding rule to allow the traffic.
I see no reason why the firewall needs to be configured to 'low' for VPN access so I'd suggest switching it off completely and disconnecting/reconnecting the PPP session before trying again.
adie:quote

[#10]

The 'recommendation' for setting to low simply means that VPN may/will be blocked at higher settings, it should work if set to 'off' or 'low'.