Cannot connect to emoncms via 2nd isp

This may be a router/firewall problem but I would appreciate some help if at all possible. I have a dual WAN firewall/router due to the pathetic speeds of my BT connection. I have a 2nd connection via 4GEE which is very fast but more expensive which I use for streaming movies etc. The other day I lost the BT connection completely and the Firewall router mostly did what it should and switched all connections over to the 2nd WAN. However my connection to Emoncms was lost until my BT connection came up again. There is nothing in the setup to stop the switchover of any of my connections and the other 30 odd IP's switched faultlessly. I realise that this is probably not an Emoncms problem but due to the large amount of knowledge here I hope somebody can point me in the correct direction.