I don’t have IBM MQ, or know it at all. There are no more descriptive error messages on the connection attempt?
Something simple to try: tcp:// instead of smf:// ?
On the Solace event broker, if you look at the event.log do you see any connection attempts?
@amackenzie is our resident MQ expert, he already provided some tips, and asked for more info / logs / errors. Any more details, please! Your exact / total config would probably help too.