First, try connecting the device in the following configuration with the WIFI adapter disconnected (if an adapter is being used):
Modem(LAN) --> (WAN)Router(LAN) --> Deeper --> PC
You will need 3 ethernet cables in total. Connect the Deeper to the PC via ethernet, not through the Router's WIFI. Once connected, wait for more than 5 minutes, then try to access AtomOS by entering 126.96.36.199/188.8.131.52 into your browser and log in with admin/admin.
Now follow the instructions in the image to manually update your firmware:
If these steps do not work, you can download this firmware and upload it to the device using the "Upload Upgrade" button shown above.
After upgrading, the Deeper will reboot automatically. Now, try to set up your Deeper between the Modem and Router.
Please wait for at least 5 minutes, then try to access AtomOS by entering 184.108.40.206/220.127.116.11 into your browser. Here are 3 videos for further reference.