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Swisscom DynDNS - DMZ no more working

Level 1
41 of 53

Hello, it was fine yesterday evening, Swisscom has correct the bug, but this morning it is already down!!!! what's play they are doing!! and no official information!!
The internet IP from the IB is not the same than the one you can found with what is my ip... it means that it is impossible to find the IB from externe, so DDNS will not work....

For exemple my IB has the and the certificate generate for my NAS (or the result from What is my IP) is

When will Swisscom solve it!!!!

Level 1
42 of 53

Still working after 24h for me. Seems to be a big mess at Swisscom...


Black Mamba
Level 1
43 of 53



To use a static IP address outside of the router's DHCP domain, it must be configured directly in the NAS by disabling automatic DHCP and entering the IP configuration fields. It must be chosen in the same subnet as the router (, but outside the DHCP domain to avoid conflicts


To do this in the router, make an assigned DHCP address static. That is to say that it is definitively assigned to this device, but the decision is taken by the router (the device is still configured in DHCP, but it still receives the same address)


For example static IP address the creation must be done manually in the NAS, not in the router. This address is in the domain of the router, but not in its DHCP area

There is nothing to configure in the router that will just serve this equipment normally

The user is then responsible for not assigning this address to several devices


The following actions must be performed:

  • Enabling Static Network IP for Synology
  • Enabling DMZ (Demilitarized Zone) on Synology
  • Spanning Tree Activation
  • Disabling IPv6
  • Redirecting router input port to Synology input port

Meilleures salutations de la Communauté francophone

Customers help customers

Level 1
44 of 53

@Black Mamba 


Thank you for your post, but I do not need a static internet IP. I have seen that the trouble from Swisscom is that they can not put the correct Internet IP to the IB and which is seen from externe.

All was working in the local net, the only trouble for DDNY is the fact that the internet IP are not similar.. like if Swisscom put an intermediate router between the IB and Internet... Strange and still the MESS....

Thank you Swisscom....

Black Mamba
Level 1
45 of 53



If the DMZ port does not suit you (which is the only possibility you have in your case), 2 other possibilities are available to you, which would be the IP passthrough, which is only available with the Centro Business 2.0 router which is normally for professionals or take a third-party router managing bridge mode


Centro Business Device and connections Learn everything about your Centro Business 2.0

for a third-party router managing bridge mode see at Netgear for example


But if you don't need 2 lan networks with different IPs, use the DMZ port, it redirects all internet traffic on it, and you wouldn't have any packet loss


on the other hand, you will need to secure your synology router as much as possible

Level 1
46 of 53

@Jioldihau39 I believe your issue is the following:

Take a look at [Carrier-grade NAT](, also known as NAT444. Swisscom is using this and in fact, this basically means that there is another router between your IB and the actual internet. You can tell that you are part of the carrier grade NAT if your public IP is (at least this was the range they used two years ago, might have changed though).

This obviously means that your router is not accessible over the internet. For this you need to have your router taken out of the garrier grade NAT, which you can do by calling support. There are some articles on what you need to tell the support to be redirected to the guys who can change this as fast as possible.

Level 1
47 of 53

Hello everyone,


Just to inform you that the Internet-Box Dyn-DNS issue is now resolved.


We apologize for the inconvenience and invite you to restart your router if it should not work.


Have a good day

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Level 1
48 of 53

Would be nice to know what caused the problem.


Wish you also a nice day 🙂

Level 1
49 of 53

Hello @Haldenwolf @Grieschauku72 @Black Mamba @Teamer16


Here is the reason communicated by our specialists:


The Internet-Box update (application part) created overload on the backend, which led to instability in the connections. Fixing the issue on the backend was unfortunately not possible, but only with an downgrade of the application part in the mass.


Have a nice afternoon

Un like fait toujours plaisir 😉 Une réponse t'a aidé? -> Accepte-la comme solution!
A like always brings a smile 😄 Don't forget to accept helpful solutions
Level 1
50 of 53

Many thanks @LeylaG .


Have a good afternoon you too.

Level 1
51 of 53

@Teamer16 You're welcome.


Thank you 🙂

Un like fait toujours plaisir 😉 Une réponse t'a aidé? -> Accepte-la comme solution!
A like always brings a smile 😄 Don't forget to accept helpful solutions
Level 1
52 of 53

Black Mamba 

The double IP is solved now. I have unplugged the booster which generate a second IP and makes troubles....


Level 1
53 of 53


Thank you so much for sharing this helpful information, it helped me alot

Thanks and regards.:) mx player for pc download

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