htaccess goof! Please help!

Hi. A while ago, I moved my domain name so I wanted to redirect all blog posts. Actually, the domains are mirrored, so basically, I just want google (and everyone else) to know to use the new name.
So I added this to my htaccess, and I think it does forward everything ok:

Options +FollowSymLinks
RewriteEngine on
RewriteCond %{http_host} ^amarcus\.com [NC]
RewriteRule ^(.*)$ https://www.AviMarcus.net/$1 [L,R=301,NC]

however, I am not sure if I copied this right, or it should be there or not…

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

My current problem is that for some time each day I can’t access the admin panel. I think I have access very early in the day. Its kinda weird.
https://www.avimarcus.net/wp-admin/ just shows: Error 404 – Not Found

What did I mess up? Can you help?
Since I can’t access the panel, I have been using live-writer to post, the xmlprc apparently is fine… It doesn’t let me add the info for the podcast though!

Thanks!!