I had some problems with client brigde until I made a firmware update with this file "wzr-hp-g300nh-dd-wrt-webupgrade-MULTI.bin" which is recommended here: http://www.dd-wrt.com/site/support/router-database?.
It is original DD-WRT without being branded by Buffalo. (DD-WRT v24-sp2 (08/07/10) std
(SVN revision 14896)?
Devices in my network:
Speedtouch ST 585 v6 as Internetgateway and AP with DHCP Server IP 10.0.0.138
Buffalo WZR-HP-G300NH 10.0.0.139
wireless physical interface ath0: client bridge
virtual interface atho.1: AP
SSID ? for both interfaces identical
wireless security WPA2 personal AES with identical keys
WAN, DHCP Server and SPI-Firewall disabled
Gateway and local DNS 10.0.0.138
under Setup/Advanced Routing:OperatingMode RIP2 Router
DynamicRouting Interface Both
I use Buffalo as OpenVPN Server and now for Wake on LAN to reactivate my PC which is linked by LAN to Buffalo
Other stuff: A NSLU2 running Samba with USB HDD as network-storage device
and a Netgear Printserver both wired on SpeedTouch Modem
3 Laptops and another PC and a Linksys Printserver all wireless
All devices in one subnet 10.0.0.
With RDP I reach all computers.The modems and the NSLU2 I can reach both via Webgui and putty.
Internetconnection is pretty quick
Port Forwarding and DynDNS is established on SpeedTouch to enable VPN Connections from outside with my laptop (UMTS mobile internet)
I checked all functions with success. The system is runnung with the new older firmware since 6.30 today morning,at the moment I can reach all devices. I am very curious if it is running still tomorrow morning.
One thing I have to mention. I wrote a startup script into my Buffalo by copy and paste after correcting the CLIENT_IP under Administration/Commands and ran it once manually before saving it. One can find the script here: http://www.dd-wrt.com/wiki/index.php/Buffalo_WZR-HP-G300NH#Fix_for_WiFi_Dropouts?
Please excuse my bad English