Laravel where method won't works correctly on my server but work right on my Mac - mysql

Question

I have a weird problem, this line wont fetch any record on my server but works all right on my computer, mysql and php version are same, and when i cast id field to string it's work on server (Debian), but it is risky because i use where statement with id very much. this is the code:
$myAnswers=Questioner::where('id',$questioner_id)->first()->getLinkedAnsweres()->where("subject_id",Auth::user()->id);
and when i change it to this, it's work right (cast id to string):
$myAnswers=Questioner::where('id',$questioner_id)->first()->getLinkedAnsweres()->where("subject_id",(string)Auth::user()->id);
subject_id and user id are both unsigned_integer with same size.
How can i fix this problem? Should i overwrite where method? or is there any config which cast unsigned int to string in query?
thanks
PS: Tables structure:
users | CREATE TABLE `users` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`name` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`family` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`username` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`email` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`gender` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`age` int(11) DEFAULT NULL,
`password` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`default_password` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`access_level` varchar(255) COLLATE utf8_unicode_ci NOT NULL DEFAULT 'subject',
`phone` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`comments` longtext COLLATE utf8_unicode_ci,
`project_limit` int(10) unsigned NOT NULL,
`questioner_limit` int(10) unsigned NOT NULL,
`created_by` int(10) unsigned DEFAULT NULL,
`remember_token` varchar(100) COLLATE utf8_unicode_ci DEFAULT NULL,
`created_at` timestamp NULL DEFAULT NULL,
`updated_at` timestamp NULL DEFAULT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `users_username_unique` (`username`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci |
answers | CREATE TABLE `answers` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`question_id` int(10) unsigned NOT NULL,
`selected_option` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`subject_id` int(10) unsigned NOT NULL,
`created_at` timestamp NULL DEFAULT NULL,
`updated_at` timestamp NULL DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci |