Umm, you mean, bypassing PA4020PKIT, wired connection and wireless connection to the router can work simutaneously? It is so strange... Try to reset both of them with utility and rename for both....

When connection drops, how about status of WAN light? Since you can login its web interface, on Status page of MR3420, WAN is showing Connecting? Provide a screenshot here. Besides, the system log...

10.68.xx.xx is a private IP. What's the IP address displayed under 3G/4G on Status page of MR3420? If it is a private IP, to fix this issue, you have to contact the ISP and it can only be fixed on...

Raj, you want the firewall connected to MR3220's LAN port to obtain WAN IP from MR3220? Cannot do that.

Can you provide the screenshot of Status page? The number after Build shows current firmware version. So it is still 120524 after firmware upgrade?

I have never heard that tplink doesn't work with N ralink dongles... And as I know, some TP-LINK adapters are also use ralink chip. You may try to update drivers of your ralink dongle.