Change Login Link

Hi,
You may use the following plugin to redirect users to your custom login page URL.
https://ww.wp.xz.cn/plugins/custom-login-url/

and if you do not want to use another plugin for this task, you may also follow the following article to get this job done.
https://premium.wpmudev.org/forums/topic/how-to-redirect-every-login-page-to-my-custom-login-page

We hope it helps.
Thanks.