SonicWall sending too many ARP requests

In the SonicWall URL replace main with diag.

For example, if you have https://192.168.168.168/main.html, it would be https://192.168.168.168/diag.html.

Select Internal Settings.

Under Arp Settings please deselect Enable gratuitous ARP Compatibility Mode.

You also have the possibility here to specify a maximum amount of Gratuitous ARP's per minute with the editable section:

Never broadcast more than (100) Gratuitous ARPs in any 60 second period.