-a 0 specifies a straight dictionary attack.

In the context of security auditing and password cracking, knowing that a standard wordlist contain a specific common password (like "password") is actually valuable data.

Here's a guide to troubleshoot and possibly resolve this issue:

john --incremental=digits hash.txt # for numeric PINs john --incremental=lowernum hash.txt # a-z + 0-9

For WPA2/WPA3, brute forcing even an 8-character password can take years on consumer hardware. Kali Linux or another OS? Do you have installed to try more advanced cracking? Are you testing a default router password or a custom one? Probable Wordlists - Version 2.0 - GitHub

Before changing your wordlists, ensure the target application is still responding correctly to your tool.