Message: "This IP is being shared among many domains"

Hello,

One (and so far only one) user which tries to access my site www.covs.nl, receives the following message:

I have checked with various utilities (MXtoolbox, IntoDNS, BrowserShots), but none of them indicates some kind of problem.
DA is set up to use shared IP, with SNI enabled and an SSL for the site.

The user is using an old iPad 1. Could this be the culprit?

It looks like that user is using an ip address in the browsers bar instead of your domain name.
If he -is- using the domain name in de browser's location bar, then he has DNS issues somehow. Maybe his old iPad1 is not able to understand the SNI/SSL combination. Maybe there is an update for his ipad?

If I remember correctly, the ipad 1 latest ios version is somewhere in the 5.x range and uses a very old (4.x) version of safari. Most likely this combination does not support sni. Your user might try another browser with the right TLS version compiled.
Or... assign a dedicated ip adres to your site.

Figured it out. My setup:

• 1 IPv4 addres, used as shared/server IP
• 3 IPv6 addresses, free, for each separate domain
• Comodo certificate for the production site, Let's Encrypt certificates for the test and acceptance environments
• Link the IPv6 address to the IPv4 address
• Be sure to have SNI turned on in directadmin.conf
• Be sure to have both the shared IPv4 and free IPv6 for each domain in the DNS settings

To verify use SSLLabs.com, where the shared IP should come up and the proper domain.