In /logs/firmware/unblob_extracted/firmware_extract/1568982-13971496.squashfs_v4_le_extract/lib/netifd/ppp-up line 4:

. /lib/netifd/netifd-proto.sh

  ^-------------------------^ SC1091 (info): Not following: /lib/netifd/netifd-proto.sh was not specified as input (see shellcheck -x).

In /logs/firmware/unblob_extracted/firmware_extract/1568982-13971496.squashfs_v4_le_extract/lib/netifd/ppp-up line 11:

	[ -n "$DNS2" -a "$DNS1" != "$DNS2" ] && proto_add_dns_server "$DNS2"

                     ^-- SC2166 (warning): Prefer [ p ] && [ q ] as [ p -a q ] is not well defined.

For more information:

  https://www.shellcheck.net/wiki/SC2166 -- Prefer [ p ] && [ q ] as [ p -a q...

  https://www.shellcheck.net/wiki/SC1091 -- Not following: /lib/netifd/netifd...