Try to increase the timeout period by adding -TO <time period in minutes>
to your command:
-S server name -D ALL -T DB -R D:\SQL_BACKUP\SQL_EXPRESSMAINT_LOGS\FULL_BACKUP_LOGS -RU DAYS -RV 5 -B D:\SQL_BACKUP\SQL_FULL_BACKUP -BU DAYS -BV 5 -TO 25
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