Surf SOHO MK III - VLAN on wired port causes cable modem disconnection



Running into an unusual problem on a Surf SOHO MK III running firmware 7.1.1. I have successfully set up and enabled two VLANs on wireless without issue. I would like to set up an additional VLAN on one of the wired network ports (port 2 to be specific)- however when this is done, the router disconnects from the cable modem (Cisco DPC321). Rebooting both the router and the cable modem does not resolve the issue. One ethernet connected PC is connected to Port 2, which has the vlan enabled in ‘Access’ mode. The Cisco DPC321 is connected to the WAN port as expected. There are other devices connected to the wired ports as well, however none of these other devices/ports are configured for VLAN support at all.

Any advice in resolving this issue would be greatly appreciated, and if I can provide any further information to help resolve please let me know. Thank you!

Cisco IP Phone VPN frequent disconnects - SOHO MKIII


Please open a support ticket to allow support team to check on this.

Suspect the issue can be related to the followings:

It would be best if you can open a support ticket to allow support team to check on it.


@mitymouse, I agree with @sitloongs that your problem looks a lot like the issue he referred you to. The good news is that there is a fix for that one if this is what you’ve got. Their very proactive support team can help you confirm this is the issue you are having.
Just one thing I would like to note: while your issue looks very similar, the original issue I was having when using the SOHO to tag VLANs on its ports, was causing cable modems to fail to recognize the router as the only device they wanted to talk to when those modems started up, and thus denying internet access to the router. However, the issue itself would not cause the router to lose an established connection to the modem, which may be what you are implying in your description. Again I think support can sort this out for you. Cheers!


Thank you sitloongs and peparn- ticket 788155 has been created.

peparn, you are correct in that the behavior is a little different, as in my case the cable modem and router are successfully connected. Upon creation of the VLAN on the wired port, the modem will disconnect and not reconnect.



Support team will followup with you via support ticket