Hello All, We are facing weird issue rarely but it continues for few hours or a day. Observations: Issue get resolved automatically when we change iOS device network. We are using sub domain for all network request on iOS/Android App, only iOS Device is logging below mentioned issue. Both domain has different certificate, where we are using wildcard certificate on subdomain, (*.domain.co.nz ) Main domain don't have subdomain name in subject list (SAN or CN) we have verified both certificate are valid and supporting TLSv1.3 Also, We have verified instruction given by apple which is also looks good: https://support.apple.com/en-us/103769 you may observer *.wordpress.com is logged in certificate chain validation But We are not calling any of the network request on *.wordpress.com Our backend server is using only NodeJs and Express.js and as mentioned by out backend team, we don't have any use of main domain/server. Here is Xcode Error Log Error Domain=NSURLErrorDomain Code=-1202 "The certificate for this server is invalid. You might be connecting to a server that is pretending to be “subdomain.maindomain.co.nz” which could put your confidential information at risk." UserInfo={NSLocalizedRecoverySuggestion=Would you like to connect to the server anyway?, _kCFStreamErrorDomainKey=3, NSErrorPeerCertificateChainKey=( "<cert(0x11603ae00) s: *.wordpress.com i: Sectigo ECC Domain Validation Secure Server CA>", "<cert(0x11603b600) s: Sectigo ECC Domain Validation Secure Server CA i: USERTrust ECC Certification Authority>", "<cert(0x116043400) s: USERTrust ECC Certification Authority i: AAA Certificate Services>" ), NSErrorClientCertificateStateKey=0, NSErrorFailingURLKey=https://subdomain.maindomain.co.nz/vider/api/v1/users/login, NSErrorFailingURLStringKey=https://subdomain.maindomain.co.nz/vider/api/v1/users/login, NSUnderlyingError=0x301ec2cd0 {Error Domain=kCFErrorDomainCFNetwork Code=-1202 "(null)" UserInfo={_kCFStreamPropertySSLClientCertificateState=0, kCFStreamPropertySSLPeerTrust=<SecTrustRef: 0x3021b1360>, kCFNetworkCFStreamSSLErrorOriginalValue=-9843, kCFStreamErrorDomainKey=3, _kCFStreamErrorCodeKey=-9843, kCFStreamPropertySSLPeerCertificates=( "<cert(0x11603ae00) s: *.wordpress.com i: Sectigo ECC Domain Validation Secure Server CA>", "<cert(0x11603b600) s: Sectigo ECC Domain Validation Secure Server CA i: USERTrust ECC Certification Authority>", "<cert(0x116043400) s: USERTrust ECC Certification Authority i: AAA Certificate Services>" )}}, _NSURLErrorRelatedURLSessionTaskErrorKey=( "LocalDataTask .<1>" ), kCFStreamErrorCodeKey=-9843, NSURLErrorFailingURLSessionTaskErrorKey=LocalDataTask .<1>, NSURLErrorFailingURLPeerTrustErrorKey=<SecTrustRef: 0x3021b1360>, NSLocalizedDescription=The certificate for this server is invalid. You might be connecting to a server that is pretending to be “subdomain.maindomain.co.nz” which could put your confidential information at risk.})) URLSessionTask failed with error: The certificate for this server is invalid. You might be connecting to a server that is pretending to be “subdomain.maindomain.co.nz” which could put your confidential information at risk. "Show: Something went wrong! please try again after sometime!" "Networking error message: Optional("URLSessionTask failed with error: The certificate for this server is invalid. You might be connecting to a server that is pretending to be “subdomain.maindomain.co.nz” which could put your confidential information at risk.") End of error Log, Kindly help us. Thanks in advance.