Plusnet User to Plusnet User Connections

[#1]

A fellow plusnet user and I had a small web server hosting things like github etc on my connection and they had similar.  Now we are unable to connect to each others, we had been successfully doing this for a year or so.

I am still able to connect to mine if I use a non Plusnet connection.

A ping trace shows DNS does resolve to the correct IP however a tracert shows that all traffic to that IP times out.

Have plusnet changed something?

[#2]

Do you both have static IP addresses bought from PN? If not then maybe the other router has been assigned a new IP. You may also want to try connecting using there pnusername.plus.com to see what that produces.

[#3]

When you say you are unable to connect to each others, do you mean by normal HTTP web browsing, or by FTP, SSH, TELNET, or something else ?.

[#4]

One possibility, is that every once in a while, some customers Plusnet network "Broadband Firewall" have been known to randomly get changed to something different from how the user last left it (and has happened to me a couple of times in 17 years).

There is a small chance that your firewall might have become set to something which blocks remote connection attempts to your modem, and therefore because the ports are blocked, your servers will be effectively unreachable.

Using this link - Broadband Firewall (Plusnet "Member Centre" login required), what is your firewall set to ?

[#5]

You could try running the Gibson Research "ShieldsUp!" port scanner to see whether your own WAN interface shows the ports you are using as being accessible remotely or not.

To do this, click on this link - ShieldsUp!, 

then click the grey [Proceed] button,

then click the grey [All Service Ports] tab(button),

and wait for the test to scan ports <0> to <1055> of your modem's WAN interface.

[#6]

We were investigating a problem that sounds alarmingly similar to this, however we're under the impression it's now fixed. Any chance you can provide some traceroutes between the two locations so we can see where the routing's falling down? Feel free to send me a private message if you're uncomfortable posting your IP's in public.

[#7]

So I want to kill a few things here.  This has been up and running for more than a year.  

We both have dynamic DNS services running and have manually validated the IP we are trying to connect to is correct.  

We have both been into our member center and turned anything port / connection blocking off (it already was). 

We have both also stuck the servers in question into the DMZ on the routers to make sure no firewall / connectivity blocking.

I can still successfully connect from a non plus net connection.

bob I will send you a PM in a  second

[#8]

Ooops, sorry I missed the bit about being accessible from a non-Plusnet connection 

I will be interested to hear @bobpullen's analysis of this strange situation. 

[#9]

I will admit I spent a good 30 minutes thinking we had done something silly with port forwarding / firewalls.

My only conclusion is I hope its not something permanent or i'll have to find a new isp 

And for reference its http traffic mainly.

[#10]

Just to give this a bit of an update.  I'm not sure of the cause at the moment, however thanks to @bobpullen we have found that if you get a new ip it seems to restore the route between us.  One of the connections had been going for 60 days however i'm not sure that is related.