The host names of the server addresses that the inverter requires for a successful Internet connection cannot be resolved to IP addresses. This may be due to an incorrect DNS setting.

Proceed as follows:

• If a static IP address is being used, ensure that the stored DNS address matches that of the router. You can check this on the user interface of the inverter under "Communication" – "Network".
• If resolution is still not possible, an external DNS can be used instead of the router's DNS address. To do this, set the DNS address in the network settings of the inverter to 8.8.8.8 (Google) or 1.1.1.1 (Cloudflare), for example.
• If resolution is still not possible, please check the DNS settings of the router.

The connection requests from the inverter to the Fronius Cloud are not being answered within the specified time.

Reasons and solutions:

• Connection is being blocked by the firewall
  Make sure that all necessary server addresses for the connection to the Fronius Cloud have been enabled in the firewall settings of the router. The complete list can be found here. If the router has access profile management/parental control (e.g., when using a FRITZ!Box), check in the settings of your router to ensure that no restrictions are set for the inverter and that unrestricted Internet access is possible.
  
  
• Weak or unstable WiFi signal
  Make sure that the signal strength at the inverter is sufficient (min. -50 dBm). The WiFi signal should be displayed on the user interface of the inverter under "Communication" – "Network" with at least 2 out of 3 bars. If the signal is too weak, switch the connection to LAN or install a WiFi repeater.
  
  
• No Internet connection
  Make sure that the router is online and that it is possible to connect to the Internet from the network.

The connection requests from the inverter to the Fronius Cloud are being rejected.

Possible cause:

• Connection is being blocked by the firewall
  Make sure that all necessary server addresses for the connection to the Fronius Cloud have been enabled in the firewall settings of the router. The complete list can be found here.
  
  If the router has access profile management/parental control (e.g., when using a FRITZ!Box), check in the settings of your router to ensure that no restrictions are set for the inverter and that unrestricted Internet access is possible.

The inverter cannot access a required Fronius Cloud service.

Possible cause:

• Connection is being blocked by the firewall
  Make sure that all necessary server addresses for the connection to the Fronius Cloud have been enabled in the firewall settings of the router. The complete list can be found here.
  
  If the router has access profile management/parental control (e.g., when using a FRITZ!Box), check in the settings of your router to ensure that no restrictions are set for the inverter and that unrestricted Internet access is possible.

It is currently not possible to synchronize the internal time of the inverter. If this behavior persists, the time will not be correct.

Possible causes:

• Inverter was recently restarted
  After a restart, it takes approx. 12 minutes for the time to be synchronized.
• Connection is being blocked by the firewall
  In the firewall settings of the router, ensure that the address 0.time.fronius.com can be reached by the inverter via port 123 (TCP/UDP).

IoT certificates are automatically renewed at regular intervals. If the server for the certificate renewal cannot be reached, the certificate will expire and the inverter can no longer establish a connection to Solar.web.

Possible cause:

• Connection is being blocked by the firewall
  In the firewall settings of the router, ensure that the address cure-se.fronius.com can be reached by the inverter via port 443 (TCP). Caution! If the certificate has expired due to missing firewall permissions, it will take several days after the settings have been corrected for the certificate to be renewed.