While building an application by python for implementing post-processing in Quantum Key Distribution, I require a server (say Alice) and a client(say Bob) at distant locations to interact and exchange some information while doing the required calculations simultaneously (for which threading is used). At first, the open-source NGROK service was used as a hosting server but it makes the time required for post-processing very huge mainly due to network congestion. So, is there a way to establish a direct peer-to-peer connection between Alice and Bob via the internet wherein Alice's system itself acts as a server thereby bypassing a third-party host server? If there is a way out please suggest one otherwise any leads or suggestions for open source services better than NGROK would be highly helpful.

PS: If you need any additional information for providing help, i would be eager to respond.