Route outbound connections from local network through VPN

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http://serverfault.com – I have a server A running OpenVPN, an OpenVPN client B (a rooted Android phone as it happens) and a third party C (a laptop, tablet etc.) tethered to B. B can use the VPN to access the internet via A; C can use the tethered connection WITHOUT the VPN to access the internet via B. However, with the VPN on B active, I cannot load information from the internet on C. A appears to log similar traffic inbound and outbound when B or C attempt to load a webpage, say, but the VPN on device B reports no inbound traffic when the connection originated from C. Where should I look for packets being drop (HowTos)