I can login with the WordPress admin account. But when I try to change to the different page in dashboard, it starts loading and loading, and then both the WordPress control panel and website aren't respond anymore. For the website part, it didn't show anything on the page, just keep loading.
It only happened after I login to WordPress and click around otherwise the website is working, is it a plugin problem?
If is the plugin problem? How can I solve and identify this issue without using FTP(still trying to figure out the way to set up the FTP with this)? Or is any other setting went wrong?
Yes, it is possible that it is a plug-in issue. You can try to disable them and access to the admin panel again. If you succeed, you could enable one by one to see which is the root cause of your issue.
In order to do so there are two ways to proceed, but both are based on deleting the wp-content/plugins folder and files since you cannot access the admin panel:
wp-content/plugins, that is the folder containing the plugin data, and to cancel it. Note that it will be enough to change the name of the in order to preserve the configs. In my case I had to do it running:$ sudo mv -f /var/www/html/wp-content/plugins /var/www/html/wp-content/plugins_oldTo locate the folder you could run the following:
$ sudo find / -name wp-contentYou can find here some documentation directly from WordPress or a different approach to disabling plugins.