The PubSub+ Messaging API for Python that you are using is an SMF (Solace Message Format) API. SMF is a Solace proprietary messaging protocol the comes with advantages when connecting to Solace brokers.
Solace brokers also support AMQP and MQTT if you want to use a open standard messaging protocol. In those cases you should use an AMQP API such as qpid::proton. There is no need to use a Solace API for open standard messaging protocols as there are many implementations to choose from.
There error you are seeing is simply the API expects SMF and is getting back AMQP.
The default port for SMF is ‘55555’ but this often is changed by the network administration and you should consult with your solace administrator for the appropriate port to use for SMF.