How many SSL certificates can be (signed) on one IP?

Question

Digital certificates

In general, 2 sites worked for me on one dedicated IP from the hoster, all of them had signed certificates, today I added 1 more site and bought a certificate for it, put it on the same IP and glitches began ...
Is this true? that 1 cert. can be placed on one IP to avoid lags? then what conflicts can be?

Answer 1

1 ip - 1 certificate.
if SNI , then 1 ip - many certificates.