DDWRT OpenVPN

Hello, I have DDWRT loaded on linksys router acting as an open VPN client that talks to openVPNserver hosted on windows server. I have other devices that connect to the DDWRT router,the DDWRT is configured as DHCP and gets its IP from the main ISP router. The problem is if the internet connection on the ddwrt resets and I have devices attached to the ddwrt I strat getting bad source address from client on the openvpn server. I am guessing the problem lies somewhere when the DDWRT is power cycled, or the main internet connection is dropped for a fraction of a second, the devices connected to it bypass the openvpn connection. I need to make sure that all devices connected to the DDWRT never bypass the openvpn connection and never get the badsource address from client on the server side. Let me know if you could help