I had the same issue: no connections with my DSL connection.
I had to upgrade the DSL connection on site B to a static IP-address (site A already has a static IP-adress): The culprit: “Carrier-grade NAT” (to spare IP-addresses) from your ISP which makes it very difficult (impossible ?) to route traffic in OpenVPN Site-to-Site mode.
See here: OpenVPN Net-to-Net issue with Fritzbox-router (Site A & Site B) - #2 by cgil
and Carrier-grade Nat:
Carrier-grade NAT - Wikipedia