How to configure static route between 2 LANs?

If the outbound interface state of a static route goes Down, the static route will be deleted from the IP routing table, but its configuration still exists.
http://www.thunder-link.com/LS-S6700-24-EI_p785.html

does this router have a lan1 lan2 lan3 lan4 ports ?
the adsl port may be for a phone line so you may need to turn off the ADSL functions in the Huawei Echolife HG520s router . Turn off the DHCP server and then plug connect lan1 to your office network. Change the ip address to be unique in your office network ip network range.
maybe 192.168.0.2 if office router is 192.168.0.1 subnet mask made the same .

Type IP address (ex. 192.168.0.10) directly into your browser...should identify it and give you some direction on the problem..

You need to plug an Ethernet cable from your router (see LAN1 or LAN2 ports) to the network card of your PC and check that your PC is using also DHCP, see here:

• http://www.wikihow.com/Configure-DHCP-in-Your-PC
  

can you clarify the switch configuration, by default it will have all ports as untagged in the default vlan 1 with a bootp/dhcp address, I assume you will need to perform some kind of routing ie; default gateway, ip-helper address or static route to point to your routing device ADSL router etc try the following;

1~ configure an ip helper address on vlan 1 to point to what ever is supplying dhcp

2~ create a defualt route on the switch ie; 0.0.0.0 0.0.0.0 to next hop / routing device

3~ configure a default gateway ie; ip default-gateway x.x.x.x where x= routing device

the above can be accomplished via a serial connection to the switch using hyperterminal with the following settings

bits per second 9600
data bits 8
parity none
stop bits 1
flow control none

let me know if this resolves the issue

You need to go to router B and configure a route to the 192.168.1.0 network with a mask of 255.255.255.0 and a gateway of 192.168.0.1.
Cheers!  

I don't know if this will help because I don't see what you and seeing but here is an idea: In every routing scenario I have experienced, you must specify a default gateway with a specific IP address. 0.0.0.0 only points to the device itself, not the other WANS. The gateway IP addresses should be statically assigned. If there is DHCP involved, insure that the gateway address is not part of the DHCP scope but in an excluded range of reserved addresses. For SMTP to work the gateways (and you should have 2 or 3) must be properly configured and TCP port 25 enabled.

There's a 9-pin serial connection on the back, can you use that connection to a terminal to see anything? Also, if you don't have access to the manual, visit this link to download the manuals: http://www.fastora.com/product_index.php?doc_name=nas-t4