Nzbgeek connection failures

Sonarr version (exact version): 3.0.3.896
Mono version (if Sonarr is not running on Windows): 6.8.0.123
OS: Mac OS X 10.10.5
Description of issue:

so, for some time (weeks from what i can tell) sonarr’s not been connecting to nzbgeek (note, i’ve not manually changed anything as far as sonarr goes; radarr’s still connecting just fine).

when i test the indexer connection within sonarr, it produces the following errors:

20-7-5 22:53:53.8|Error|X509CertificateValidationService|Certificate validation for https://api.nzbgeek.info/api?t=caps&apikey=(removed) failed. RemoteCertificateChainErrors
20-7-5 22:53:53.8|Warn|Newznab|Unable to connect to indexer

[v3.0.3.896] System.Net.WebException: Error: TrustFailure (Authentication failed, see inner exception.): 'https://api.nzbgeek.info/api?t=caps&apikey=(removed) ---> System.Net.WebException: Error: TrustFailure (Authentication failed, see inner exception.) ---> System.Security.Authentication.AuthenticationException: Authentication failed, see inner exception. ---> Mono.Security.Interface.TlsException: CertificateUnknown

20-7-6 00:29:39.3|Error|X509CertificateValidationService|Certificate validation for https://api.nzbgeek.info/api?t=caps&apikey=(removed) failed. RemoteCertificateChainErrors
20-7-6 00:29:39.3|Debug|NewznabCapabilitiesProvider|Failed to get newznab api capabilities from https://api.nzbgeek.info

[v3.0.3.896] System.Net.WebException: Error: TrustFailure (Authentication failed, see inner exception.): 'https://api.nzbgeek.info/api?t=caps&apikey=(removed) ---> System.Net.WebException: Error: TrustFailure (Authentication failed, see inner exception.) ---> System.Security.Authentication.AuthenticationException: Authentication failed, see inner exception. ---> Mono.Security.Interface.TlsException: CertificateUnknown
  at Mono.AppleTls.AppleTlsContext.EvaluateTrust () [0x000c7] in /Users/builder/jenkins/workspace/build-package-osx-mono/2019-10/external/bockbuild/builds/mono-x64/mcs/class/System/Mono.AppleTls/AppleTlsContext.cs:307

[v3.0.3.896] System.Net.WebException: Error: TrustFailure (Authentication failed, see inner exception.): 'https://api.nzbgeek.info/api?t=caps&apikey=(removed) ---> System.Net.WebException: Error: TrustFailure (Authentication failed, see inner exception.) ---> System.Security.Authentication.AuthenticationException: Authentication failed, see inner exception. ---> Mono.Security.Interface.TlsException: CertificateUnknown

i’ve search the discourse for others having this. updating mono seems to be their answer, but my mono’s fairly up-to-date, and as stated, radarr’s not having this issue.

Exact same issue on my end - Radarr fine, Sonarr had this error for a while. Other indexers using HTTPS also working fine, only NZBGeek with the error.

I have updated Mono framework, also reset certificates in SABNZB, no change.