That is normal for our UBlockers.  Our devices are designed to stay in 'passive' mode until they receive incoming calls.  The local connections to the local routers may disappear (e.g. not show as active devices) depending on your local router's cache time-out settings.  There is a simple test you can do in order to make sure your UBlocker is working properly.  Here it is:
1) First add your cell phone to the Blacklist
2) Wait until the UBlocker disappears from the list of active devices on your router.

3) Make a test call from your cell to your landline where the UBlocker is connected.
If the call is disconnected, your UBlocker is working properly.  If not, please let us know.

Note: Please remember to move your cell phone number back to your Whitelist.