[Multisite] [Subdomain] Disable SSL for one site without a wildcard cert

Hello everyone,
I’m setting up a subdomain multisite on my wordpress site.
My principal domain is under SSL as it handles payment.
My subdomain wont handle any payment and doesn’t need SSL.
When setting up multisite, I can’t manage to set SSL for only my main site. The url in the menu to switch sites all include https://, when I would want it to be http://.
I’ve tried setting up some rewrite rules in htaccess, but it doesn’t seem to work, and I’d rather have the correct URL in the wordpress links than use a rewrite rule. I’ve tried setting up ReallySimpleSSL plugin on my network, doesn’t seem to solve my issue either.

I also have a weird issue where I can see my multisite sites on my main site, but when I switch to the management console on the second site, I don’t.

Any clues ?

Thanks !