If you have Direct Connect option on - everyone who will connect to you with either steam or gog server browser - will try to connect you directly with help of our servers and avoiding slow steam relay. Depending on your network settings (NAT type for example, port forwarding) connection may be successful or not - if it is not steam will use matchmaking system you have - so it will fallback to steam or gog. There is significant difference in speed between direct connect and Steam. If you have 54 kb/s - it means that you fall back to steam due to inability to connect with stated client.
In case you want someone from gog to connect your steam version the only way is direct connect. Since steam and gog do not have shared infrastructure its impossible to connect you via matchmaking system. For that you will need to manually give a direct connect ID to a person who wants to join you. There is small button near the option in Connectivity Menu allowing you to copy in your clipboard. Sadly - you right and you can't paste in Chat UI. Thats we aware - sorry for inconvenience
