Port 53 restarts the Router randomly

[#1]

Hi All,

I have Virtualmin (webserver) that I do development testing work on and have noticed that each time I create a Webspace the router restarts (WiFi Drops then router seems to restart - or at least lose internet connectivity for a brief time) - Running tests I have discovered that it appears that port 53 is the culprit, which of course cannot be removed as its the DNS for the nameservers connecting the domain to the Virtualmin server. My question is, has anyone else had this issue before and if so what did you do to fix it? I have contacted Plusnet and they sent another router out to me, but same thing is happening. I am not sure if its the Plusnet Hub One router causing the issue or some other underlying issues with my connection.

Any help/advice would be most appreciated.

Thanks

Plusnet Hub One | Software version 4.7.5.1.83.8.237.2.2 | Last updated 04/04/18

[#2]

Moderators Note.
Moved to 'My Router' from 'Fibre' as it seems to be a hardware issue.

[#3]

'running tests' - can you elaborate?

[#4]

Sure.
So I have created a separate port forwarding rule that virtualmin requires with all the relevant ports open. When I discovered that the router resets I started one by one taking out the ports from the rule and adding them again. IE removing all rules adding them one at a time until I found the one that caused the issue. Once I found that port 53 (all flavours of it) was causing the issue, I removed it and created it in a separate rule. Disabling the main rule virtualmin rule and trying again. It seems that something either the router or the plusnet DNS ips (that annoyingly can't be changed) are somehow blocking the connection and thus forcing the router to restart. I'm not sure if plusnet DNS is thinking that my router is getting DDoS'd and forcing a restart but it's very strange nonetheless. I hope that clears things up a bit.

[#5]

Are the DNS rules currently disabled? Not particularly familiar with Virtualmin, however what exactly is it configured to respond to on port 53? It sounds to me that you may be at risk of running an open resolver i.e. allowing your server to respond to all external DNS requests regardless of origin. If this is the case then it's very bad practice, and extremely open to abuse.

[#6]

Thanks Bob, but I am not quite sure what you mean or how to correct it. The virtualmin instructions say to open some standard ports as well as port 53. Virtualmin is a Ubuntu box with Apache and mysql. Are you able to explain a bit further as to what you mean thank you.

[#7]

It might be worth you messaging me with step by step instructions and I can try replicating here. Virtualmin is open source, so shouldn't be too tricky. At the moment, you're not running an open resolver, but that could well be because the port 53 rules are disabled.

[#8]

Thanks Bob. I shall PM you. Hopefully we can resolve it.

[#9]

Hi Bob,

I have now PM'd you 2 messages, one has the information to set up virtualmin the other is a video to show you what happens when it creates a new domain. - Let me know if you haven't received them.

Thanks