Once the activation process completes, you would need to make sure to restart the watch by press hold the 3 buttons together and go to setting and switch on "Data Roaming" and ensure the APN setting is 1-first.
In case you do not see APN on watch setting list, proceed to remove and reinsert the SIM card and restart the watch.
Above image shows no 4G sign shown as network is not detected.
Once watch is able to detect network, 4G sign will be shown on the watch main screen.
You may contact our customer support at firstname.lastname@example.org if the issue persists.