I used multisite sometimes before but never used the network settings. And I wasted an hour because of the lack of knowledge about multisite.
I set both upload_max_filesize and post_max_size to 256M in
php.ini files (I did this many times, can be wrong), but when I upload, it always shows Maximum upload file size: 1 MB. I tried to restart the server, add value to
wp-config.php file, but it still didn’t work.
But, wait, I had uploaded an over 2MB plugin to this site some days ago without any limit. An idea flashed in my head: “That’s it, multisite.”. And I asked Mr. Google
"upload max file size wp multisite" and figured it out. I completely missed the “Max upload file size” setting in
Network Admin > Settings > Network Settings.
Hope that no one stupid like me.