The problem with speedtest-cli is that the servers are set up to test domestic accounts, not other servers. You can be lucky and get ~1GBs bandwidth, but just because you don't doesn't mean that it's the fault of the provider. The server specs and speedtest only require a 1Gbit/s port, so you will probably not get higher results than yours anyway.

Network speed should generally not be the issue with AWS, it's disk iops where the non-local SSDs will make a major impact.