Showing results for 
Search instead for 
Did you mean: 

Internet-Box plus DNS resolution very slow

1 of 11



I have been using an Internet-Box plus for a few years without any major problem.


Now, ever since the latest firmware 08.08.26 has been pushed to my router, I am noticing a considerable delay in DNS resolution of hostnames, which of course considerably slows down opening webpages.


I have finally decided to install a BIND9 DNS server on a local Linux machine I have, and DNS resolution time is back to normal.


Of course this is an issue for all the devices on the network, made even worse due to the impossibility of changing the DNS server address which the DHCP server inside of the Internet-Box sends to the DHCP clients.


I would have to manually change the configuration of every device, and that is clearly an additional complication that I would like to avoid.


I thus raise two points:


1- am I the only one noticing that DNS resolutions is especially slow since firmware 08.08.26 was installed?


2- would it be possible to add an expert configuration item in the DHCP configuration to point the DHCP clients to a DNS server different than that on the DHCP server itself?


Many thanks, Luca

Super User
2 of 11


  1. no, how do you measure? ns lookup and you measure the time?
  2. AFAIK you can configure a specifiy DSN Server. did you check your router settings unter



3 of 11

1) same here. "tracert" always stuck at the 5th step

2) not sure I understand that. The settings let you change the DNS servers. But sadly without any effect (with google's and for example)

Super User
4 of 11

on the GUI of your internet box, you can change the DNS server.

Otherwise you can also change it locally on your clients.

5 of 11

Thanks for your answer @suisse.

The issue is still very much there, in spite of any changes to the DNS configuration on the Network Expert tab.

In fact, I am not even sure what that configuration is about, other than maybe the DNS servers to which the Internet-Box forwards the DNS queries coming from the clients on the network.

As a matter of fact, the DHCP replies *always* have the local IP address of the Internet-Box as DNS server, and thus the only way to change the DNS servers on all the clients will be to disable the DHCP server on the Internet-Box and install and configure one on a Linux box, so that a more configurable DHCP server is available on the network.

The proof of the issue is in the fact that on the machines where I have changed the DNS server configuration manually, things are back to normal in terms of speed of DNS resolution. Not so on those machines who point their DNS queries to the Internet-Box for further upstream resolution.

6 of 11

@adi77 the first issue you face might not be related to DNS much at all. Try to add the '-n' option to disable DNS resolution and see if it works. Oftentimes intermediates routers do not properly match a reverse DNS query.

On the second issue I agree with you, I think that box is only used to configure the upstream DNS servers to which the Internet-Box forwards the DNS queries. But changing the DNS servers there does NOT change in any way the issue with speed of DNS resolution.

7 of 11

I dedicated a bit more time to this issue I have been facing for a while, and hopefully have solved it for good.

All it took was a reset to the default settings of the Internet-Box, after having saved the configuration locally on my machine, so that it took little effort to restore all the many changes I had implemented in the configuration, especially the MAC address bindings to static IP addresses.

One of the things I have noticed is that the IPv6 configuration setting was not saved in the configuration file, and I had to turn on IPv6 by hand after restoring the old configuration file.

Now, after the reset to the default configuration, uploading the old configuration files and changing back the DNS servers to the default ones from Swisscom, things seem to be back to normal in terms of DNS resolution speed. Pheew!

Ciao, Luca

New Member
8 of 11

Hey Luca! I had the exact same issue. Everything was fine when using the work VPN, so it also pointed me to suspect DNS problems. Your solution seems to work. Thank you! 

Sergii K.

New Member
9 of 11

Also, indeed, setting google dns servers did not help at all.

10 of 11

Hi Luca.

I am glad I'm not the only one. I had exactly the same problem for the second time in two month. Internet getting slow until a point where name server lookup doesn't work anymore: browsers time out (but accessing the router via of course work well).

Swisscom box shows everything is ok but in reality it cannot itself perform the initial ping test of the built-in speedtest (this should work even if the speed test servers aren't available).

nslookup times out. Ping the name server works well (15 ms -

reboot the router won't do anything, until you reinitialize (2+ seconds reset enough - not the hard reset).

reboot takes in the area of 6-8 minutes with a lot of blinking white and red.

immediately after the reset, nslookup works perfectly again.

Because the router's diagnostics are all green, Swisscom personnel deny any issue with their service and therefore only offer fee-liable online service (closed on weekends) or call-in engineers.

Bests, pascal

11 of 11

Hi Pascal,

I had to do once again the whole reset to factory default then restore of the last configuration, and things are now working well again.

It definitely looks like the box starts to slow down at some point in time, with DNS resolution being the first indication of the firmware acting up.

I have been experencing very slow GUI access to the box, and often times the GUI just says to reconnect to the box again.

I was also trying to update iOS on an iPhone I have, and the Apple servers could not be reached.

I then did the factory reset and restore of the configuration, and everything is working well again.

And in two weeks time I know that I will need to do the same thing again... I am tempted to try the new Internet Box, but I don't want to spend the money to get the new one, especially as the software issue might still very much be there, in spite of the likely hardware differences.

Go figure...

I don't even bother to contact the Swisscom technical support on such a topic, it would be a waste of my time I am afraid.

Bye, Luca