While ASCII-art is normally OK, here, I am not sure even how many sites in total we are talking about. So unless the PC1 and the Mikrotik are located at Site A whereas PC 2 and the “VPN server” are located at Site B, can you attach a photo of a handmade sketch with a more detailed structure? What kind of device is the “VPN server”, another Mikrotik or something else, are you the administrator of that one too? Is PC 2 connected to the LAN of the “VPN server” or is it its remote client?