Virgin business hub periodically refusing to resolve DNS requests for clients

[davids355]

First of all, I am contacting you guys on behalf of a business customer - I hope it is OK to be posting here with my issue.

Secondly, to my issue - I have a Hitron router provided by Virgin and a strange issue in that, every now and then (Normally every couple of days) the router stops providing a response to DNS queries from client devices. The result for the end user is that the internet stops working until the router is restarted.

I am an IT engineer providing support on behalf of this particular client and as such, I have done some troubleshooting as follows - 

First of all, I have established that it happens every couple of days and once the issue occurs, it will not resolve itself until the router is restarted.

Secondly, if I do a ping test from the routers web portal, the DNS works as expected - for example I can use the ping command in the routers web portal and put in google.co.uk, to which it will reply with the google IP address, as expected. So the router is not down as such, it just refuses to give this information to clients.

To stop the issue from causing too much of a problem, I have now assigned static DNS addresses to the client computers - 1.1.1.1 for primary and 192.168.2.1 for secondary. This means they can still function when the DNS stops working on the router.

To continue troubleshooting the issue, I ran an nslookup command from the client devices as follows - 

nslookup google.co.uk 192.168.2.1 (The routers IP address).

When its working, the command returns the correct IP, but once it stops working, I get the following error - 

puma7-atom.hitronhub.home can't find google.co.uk: Query refused

I have contacting virgin business support about this issue. They could not find a problem and even when the issue was occuring, they could not see any issue on the router from their side.

They have since sent out an engineer, who couldnt find anything wrong either. Interestingly, when the engineer was just about to leave, the router stopped giving out IP addresses to clients and so, the engineer decided to put in a new router - we configured this new router manually rather than restoring a backup from the old router.

I assumed that would be the end of the issue but two days later, the issue has reoccured.

Now I am really at a loss as to what it could be causing the problem?

The only changes I have made to the routers standard setup are to put it on a different subnet - 192.168.2.0/24 and to change the wireless SSIDs to our own custom ones (for 2g and 5g respectively).

I really can't think what could be causing this, other than perhaps some bug in the routers firmware that only occurs when the router doesn't have its default LAN settings in place? Or there is something on the network intefering with the router, but I really don't know where to start troubleshooting with this one, other than perhaps when it next goes wrong, I might remove all other devices and connect just a single computer directly to the router then see if the DNS resolution still fails - at least then I could rule out inteference from another device.

Any thoughts on what else could be causing this, or anyone else seen anything similar?

[davids355]

For reference, here is a screenshot of the output from my nslookup query -

https://imgur.com/TDTMv4B

[legacy1]

Just bad firmware VM do not test stuff that well

put in modem mode get your own router
https://www.virginmediabusiness.co.uk/help-and-advice/products-and-services/hitron-router-guide/dyna...

[davids355]

thanks I will do that, in that case

[itconsec]

It is like I wrote that post!!

I have had the exact same issue with one of my clients and been through the mill with VM support. I spoke to one tech support who admitted it was a known fault with a firmware release but this has since been retracted by another tech support who said they have no known issues! They keep sending engineers out who either change the router or factory reset it and go on there way claiming to have solved the problem without waiting the few hours to  know the exact same issue will reappear. 

I have seen some planned maintenance on all of my customers for 27th July for 5 minutes, hoping this is the push for the fix.

s a side issue, does anyone else have issues with security questions when phoning in, what was correct one day is wrong the next (ie business name!) it is very frustrating.

[davids355]

Good to hear that its not just me going mad then. After the first engineer came out (He was very helpful and knowledgable in terms of cabling and infrastructure but did not know much about router firmware etc) I gave up calling Virgin as I didn't feel it was likely to get a result being such an unusual issue.

For the record, what i done was to put a router in between Virgin hub and the rest of the network - rather than switching to modem mode though (As I don't think thats easy if you have a static IP) I just turned DHCP off on the virgin modem, then configured my own router to provide DHCP leases - BUT using the virgin hubs IP address as the gateway.

This effectively leaves my router providing DHCP AND DNS resolution, whilst the Virgin hub is purely providing gateway access. So far, this has been working well and what is really strange is this - Before I made those changes, I had a script running on one of the computers that would send a DNS query to the virgin hub every few hours (Using NSLOOKUP) and then send me the results - whilst the issue was ongoing, I would see every few days the Virgin hub started to refuse these queries (And a reboot would resolve the issue temporarily), but after I put the revised system in as per above, I kept this script running and the Virgin hub stopped refusing these requests.

I don't know how what I have changed would have impacted the issue, its almost like the hub can only deal with so many DNS queries before it starts rejecting them, or perhaps it is mistakenly blocking requests as being malicious after there are so many? The only thing that has changed on my network, as far as I can see, is that I am no sending no requests for DNS resolution to the hub (Apart from when my NSLOOKUP script runs every few hours).

Anyway, if you have any progress on the issue yourself, please post here as I would be interested to hear.

[Ilyas_Y]

Hey there @davids355, thanks for reaching out to us.

I'm sorry to hear about the issues with the business side of things.
As we are residential over here, we have limited access in what we can do.
To speak about a business account, please contact: 0800 052 0800 and our team will assist.

Let us know how it goes.

Kind regards.