Background Information
A static IP may need to be set on inverters for sites where Dynamic IP addressing (DHCP) is not available, either due to network security reasons or as a result of an issue. A static IP address will also be needed if there are DNS (Domain Name System) resolution issues which require changing the DNS server IP. For such issues, please refer to the following article: DNS Server could not be resolved

Requirements
Depending on the connection type, you may need to set a static WLAN or Speedwire (Ethernet) IP address. The following information is required to properly set a static IP:

• IP Address
• Subnet mask
• Gateway IP
• DNS server IP

Procedure

1. Log in to the inverter's WebUI as either installer or user.
2. Navigate to 'Device Parameters' (in the top menu).
3. Click 'Edit Parameters' .
4. Scroll down to 'System Communication' and open the drop down menu to view the WLAN (Wifi) and Speedwire IP Settings.
   
5. Set a static IP address by entering the desired IP settings and change Automatic configuration switched on from Yes to No.
   Note: The default IP settings shown in the fields do not reflect the current IP settings. These are just 'placeholder' values stored in the inverter. The current IP settings can be found in the WebUI menu: Instantaneous Values > System Communication. See screenshot down below for an example (shows static IP of 192.168.1.10:
   
6. To apply the new settings, scroll to the top of the page and select Save all.
   

https://my.sma-service.com/s/article/Setting-Static-IP-Addresses-on-SMA-Inverters?language=en_US