Cannot connect after Availability Group automatic failover
If you cannot reach the listener from SSMS, then it seems to be an issue with networking or name resolution (DNS).
You can try do to a NSLOOKUP of your listener and make sure it point at the primary node. If not, it means you have an issue with DNS update. Your windows admin should be able to help you.
If it points to the right server, but you cannot ping it or connect to it, then I would provide that information to the network team, asking them to assist with this specific situation.