This issue is often caused by network settings. First, please try restarting your ONU (Optical Network Unit).
If the issue persists, please try the following steps in order.
Please note that the configuration screens may differ depending on your ONU or other devices, so we are unable to provide detailed instructions for every case.
1. Disable IPv6 from the ONU's configuration screen.
2. Set the firewall level to "Low" from the ONU's configuration screen.
3. Disable IPv6 on your PC:
・Control Panel > Network and Internet > Network and Sharing Center > Open your network connection device > Properties > Uncheck IPv6
4. Open UDP ports from your router's configuration screen:
(i) Open the "Port Forwarding" or "NAT Settings" section
(ii) Add a rule to open UDP ports 1024–54435. If you cannot set a range, try opening ports 1024–65535 instead. Refer to the following article for more detailed instructions on opening ports.
How to open UDP ports – Warlander Support
Please also note that this issue is often temporary. If the above steps do not resolve the problem, we kindly ask that you wait for a while and try reconnecting again.