From the debug.log located at …\Trend Micro\Apex One\Addon\TMSM folder:

2020-05-28 10:04:54 71420257 [15] DEBUG TMSMMainService - [GetTMSMWebUrlforTest] TMSM web url for test: (https://[apex one FQDN]:4343/officescan_tmsmconsole/osf/v1/Test)  [0]
2020-05-28 10:04:54 71420257 [15] DEBUG TMSMMainService - [SendHttpRequest] Request data content({})  [0]
2020-05-28 10:04:54 71420257 [15] DEBUG TMSMMainService - [CertificateValidationCallback] Certificate error: RemoteCertificateChainErrors  [0]
2020-05-28 10:04:54 71420257 [15] DEBUG TMSMMainService - [CertificateValidationCallback] ChainStatus[0].Status: NotTimeValid  [0]
2020-05-28 10:04:54 71420257 [15] DEBUG TMSMMainService - [CertificateValidationCallback] ChainStatus[0].StatusInformation: A required certificate is not within its validity period when verifying against the current system clock or the timestamp in the signed file.
  [0]

The issue happened because the certificate that is in used in IIS is expired.

To resolve the issue:

1. Go to the IIS manager.
2. Navigate to Sites > Officescan > Bindings > https > Edit.

   

3. From the SSL certificate, change the certificate by clicking select and choosing the valid certificate.
4. Click OK.

   

5. Restart the Apex One Mac Main Service and Apex One Master Service.
6. Verify if the web console is now accessible.

To verify if the web console is accessible:

1. Navigate to IIS manager > Sites > Officescan > Bindings > https > Edit.
2. From the SSL certificate, click view then check the expiration date.

   

3. Verify if the Apex One Mac console is now accessible.

If the issue still persists, kindly collect the complete Apex One server CDT logs under the …\Trend Micro\Apex One\Addon\TMSM folder and create a Trend Micro Technical Support ticket.