You can use the asterisk "*" as a wildcard.
Specify the wildcard at the octet level, such as "198.51.100.*".
You cannot combine a wildcard and numbers within an octet, such as "198.51.100.1*", to specify a wildcard for specific digits.
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Related: Please tell me about access restriction by global IP address (Group IP Restrictions and Folder IP Restrictions)
https://help.teachme.jp/hc/en-us/articles/900005508766