You can find the following messages in domainmanager.log. SDDC Manager subtask view also shows the error message such as VIRTUAL_APPLIANCE_NTP_CONFIGURATION_FAILED.
YYYY-MM-DDT09:44:31.690+0000 DEBUG [vcf_dm,68dcf7f20cb86372b502b0f9ecada4af,4df9] [c.v.e.s.r.c.LoggingHttpRequestInterceptor,dm-exec-12] Request URI: https://<SDDC Manager FQDN>/lcm/lcops/api/v2/settings/system-details/time
Request method: POST
Request body: {"syncWithHost":false,"ntpServerEnabled":true,"ntpServerStarted":false,"ntpServers":"###.###.###.###"}
Response code: 400 BAD_REQUEST
Response headers: [Date:"ddd, DD MM YYYY 09:44:31 GMT", Content-Type:"application/json;charset=UTF-8", Transfer-Encoding:"chunked", Connection:"keep-alive", Set-Cookie:"JSESSIONID=###; Path=/; HttpOnly; Secure; HttpOnly; SameSite=Lax", X-Content-Type-Options:"nosniff", X-XSS-Protection:"1; mode=block", Cache-Control:"no-cache, no-store, max-age=0, must-revalidate", Pragma:"no-cache", Expires:"0", X-Frame-Options:"DENY", Content-Security-Policy:"script-src 'self'", Strict-Transport-Security:"max-age=31536000; includeSubDomains", Lcm-API-Version:"8.0"]
Response body: {"status":"ERROR","statusCode":"BAD_REQUEST","message":"Please check if the provided IP/FQDN is of an NTP server and is reachable.","resourceIdentifier":null,"errorCode":0,"errors":null}
YYYY-MM-DDT09:44:31.694+0000 ERROR [vcf_dm,68dcf7f20cb86372b502b0f9ecada4af,4df9] [c.v.e.s.v.ConfigureVirtualApplianceNtp,dm-exec-12] Configuration of NTP ###.###.###.### servers for VM <<SDDC Manager FQDN>> failed
YYYY-MM-DDT09:44:31.705+0000 ERROR [vcf_dm,68dcf7f20cb86372b502b0f9ecada4af,4df9] [c.v.e.s.o.model.error.ErrorFactory,dm-exec-12] [######] VIRTUAL_APPLIANCE_NTP_CONFIGURATION_FAILED Failed to configure NTP on virtual appliance <SDDC Manager FQDN>
com.vmware.evo.sddc.orchestrator.exceptions.OrchTaskException: Failed to configure NTP on virtual appliance <SDDC Manager FQDN>
SDDC Manager 5.2.1
Aria Suite Lifecycle can not reach to NTP server which is configured in SDDC Manager.
Check if Aria Suite Lifecycle can reach to the specified NTP server. If you have VLAN-Backed AVN (Application Virtual Network), you may need to configure the VLAN trunk on the physical switch.