Reference:
https://docs.microsoft.com/en-us/azure/vpn-gateway/troubleshoot-vpn-with-azure-diagnostics IKEDiagnosticLog = The IKEDiagnosticLog table offers verbose debug logging for IKE/IPsec. This is very useful to review when troubleshooting disconnections, or failure to connect VPN scenarios.
GatewayDiagnosticLog = Configuration changes are audited in the GatewayDiagnosticLog table.
TunnelDiagnosticLog = The TunnelDiagnosticLog table is very useful to inspect the historical connectivity statuses of the tunnel.
RouteDiagnosticLog = The RouteDiagnosticLog table traces the activity for statically modified routes or routes received via BGP.
P2SDiagnosticLog = The last available table for VPN diagnostics is P2SDiagnosticLog. This table traces the activity for Point to Site.
https://docs.microsoft.com/en-us/azure/vpn-gateway/troubleshoot-vpn-with-azure-diagnostics