what mode is 4300's WAN port working as? what is the detail issue phenomenon. when your devices lost connection, has the WIFI icon missed? why not go to wireless statistic to check if your devices...

did you upgrade the firmware? you can check the association speed on your wireless devices, and see if the association speed is low. besides, how many clients are there connected with C5? you can try...

try to change your wifi router1's LAN IP to 192.168.10.1, then change a different SSID of router1, and enable DHCP server in the mean time, reset C7, disable DHCP server, and set WDS for bridging...

try reset your C50 first, and upgrade the frimware