The current domain for our Site is my<companyname>.force.com/<sitePrefix> and we re-branded, so I am setting up a custom domain & custom URL with a new name.

I set up order.<companyname>.com as a custom domain, and assigned it to the Site with

order.<companyname>.com/<sitePrefix>

When I added this custom URL, the following perfect things happened:

 - All URL redirects that were in place for /<sitePrefix>/somePage ----> /<sitePrefix>/someOtherPage
Continued to work, except with orders.<companyname>.com/<sitePrefix>

 - The old domain continued to go to the Site, but the URL was then replaced with the new one. Great!

My one problem:

Logout doesn't work. I can see that the Site's template/code for logout is "{!$Site.Prefix}/secur/logout.jsp"
Since the site prefix is the same, I can't understand why I'm having issues with the logout functionality.

Detail on what happens on Logout with the new domain:

When you first login, you are brought to a home page. When you click logout after the new domain was added, instead of logging out, it just brings me back to the homepage. When the credentials expire in the browser eventually, it just brings you to the home page still (rather than login screen) only no data is available since nobody is authorized.

-----------------------------------Personal Disclaimer if this question is stupid----------------------

I had a rough experience with creating a Community and an unexpected redirect (in Production) and Support with Salesforce went on for two weeks with NO valuable feedback or information, so I want to avoid anything unexpected/irreversible since I can't rely on support.

Furthermore, custom Domains need to be done in Production, as they are not supported in dev orgs, which is another reason why I need to be sure of what my impacts are before proceeding
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So! Domains >> New Domain >> I have a CNAME set up and all that jazz, I just need to hit save and activate. This doesn't automatically change the URL for my communities, right? That would be done manually? Sorry if this is a dumb question, I'm just very skeptic of Salesforce with Domains from the last 2 weeks on the struggle bus. I want to confirm that nothing will automatically happen just by creating this domain.

Bonus question... if I assign this Domain to a Site using Custom URLs, this too does not change any other communities/site URLs, right?

Thank you!

Note: This may not be very developer related. I think it's purely configuration. But Support told me this was out of scope and I need developer support, which I am not eligible for, and pointed me here. My apologies if this doesn't quite fit, but I need help.

A domain I have in salesforce - mysightlife.force.com - would automatically redirect to mysightlife.force.com/surgeonportal. It is a redirect that is set up to do so, and points to the Community site.

I wanted to investigate how to make a custom domain for this Site, and found out you cannot do so in Test Environments. So, I figured I could make a *separate* community in Test (which shouldn't affect the current URL redirects at all) and use this to test out a custom domain for this other site.

WELL, When I created mysightlife.force.com/nataliescommunity , all of a sudden, just by creating it, mysightlife.force.com automatically stopped redirecting to /surgeonportal, stayed the root domain, but displayed an error page that stated nataliescommunity is down for maintenance. This was customer facing! There were no redirects to nataliescommunity set up. and the URL at the top was NOT mysightlife.force.com/nataliescommunity -- it was simply the root, and showing this page. In my other Site, redirects were still active to direct root to /surgeonportal.

I ended up going into this new Site and adding the URL redirect from root / to /surgeonportal, which worked, but I need an understanding of

1 - what happened? Why did the domain automatically associate with this new community?
2 - how to undo this so there is NO association with this new community
3 - why was the community inactive, but the site active? How do I delete this?