RBR50 / RBS50 intermittent routing problem

There's no correlation with power outages and I've no way to replicate the problem at the moment, it seems to happen at random.

It may be a 'creative' solution to attach the server to a satelite rather than the router but given the location of the server and the fixed placement of my WAN modem by my ISP I have no choice. This config has worked almost flawlessly for 9 months and continues to work 90% of the time even now. I see no reason why it shouldn't work either.

I'm aware of how DHCP is meant to work, maybe I should be more specific and clarify that:

1) In the cases a client doesn't get a DHCP address while connected to RBR50, if I give it a static address in the OS and try to ping the IP of either RBS50A, the server or any other device connected to RBS50A I receive no reply. If I ping RBS50B or any WAN IP address I receive responses as expected, hence this is only an issue routing traffic to RBS50A. An initial DHCP request may be a broadcast packet in itself but the complete handshake and allocation of an address does involve the use of routing protocols.

2) Sometimes the problem occures when my client device already has an IP address leased and I experience problems as I have lost connectivity to my DNS server i.e as above  while connected to RBR50 and I try to ping the IP of either RBS50A or the server I receive no reply. If I ping RBS50B or any WAN IP address I receive responses as expected

That DHCP implementation does seem a little odd but as I'm not seeing any evidence of IP address conflicts I don't see that as being the cause of the problem.