Hello   The message indicates that the browser does not like the certificate authority. OMSA uses a self-signed certificate. Many browsers see this as a potential security issue. Thanks
What are the correct strong ciphers to stop getting the NET::ERR_CERT_AUTHORITY_INVALID and This server could not prove that it is xxxx; its security certificate is not trusted by your computer's operating system. warning when opening OMSA. We use the current version of chrome by default.  I was poking around in the OMSA web server settings and it seems to me the issue is the tsl1 and some leftover SSL options in the cipher strings and the fact that it is using 128 instead of 256. I know at one point the old fix involved removing the ciphers that used dhe_rsa and now I am wondering if the issues are 128 vs 256 with the browses along with some residuals SSL vs tls1 ciphers remnants left in the ciphers even though the protocols choices selected are tlsv1.1 and tlsv1.2 OMSA ver is 8.5. My other servers are doing the same thing using various other versions of OMSA. 
OMSA Web server certification cihpers