E2121 - No service found for serviceport

The E2121 - ECE_SOAPFaultResponse: We received an error response from the server: FaultCode: Server String.....: serviceSubscriptionInfo: no service found for serviceport: xxxx and ip_address: xx.xxx.xxx.xxx error occurs because the hybrid system maintains a local copy of the configuration, including an expiration date. When a service subscription is renewed, a new expiration date is assigned, which can cause a mismatch with the locally-stored configuration, triggering this error. One solutution is to click on Activate Changes on one of your active connections so the updated configuration is downloaded into the hybrid, together with the new expiration date. 

However, one key factor to investigate is whether your network uses different IP addresses for inbound and outbound traffic and make sure that it's the same. To be noted that this issue only occurs upon subscription renewal.