WA801ND is working in AP mode? What's the firmware version of it? Is it up to date? How did you figure out that the problem is caused by WA801ND? Bypassing it, no problem at all? Provide the topology...

Do you need any kinds of authentication when configuring WR702N to repeat Wi-Fi signal from BT Wi-Fi hotspot? What have you tried before you restore the system? Did you remove network profiles and...

What's the problem? I don't think it supports SIP ALG.

It sounds like the problem with your laptop itself. Are you connecting to W8968 by wire or wirelessly? Any other clients like a phone or tablet for you to set up W8968? Where did you see the error...

Firmware is up to date? Did you try to reset it? Try different web browers and different clients to set it up. If it is the same, take it back to the retailer and ask for a replacement.

What's the IP address obtained when connecting to powerline adapter and to your router directly? The utility can detect the remote powerline adapter? Did you try to reset both of them?