@Kupsul Hi, is your ISP modem a pure cable modem or modem-router combo? If it is a router, it is ok to connect two E4 units together; And it is also suggested that you could switch the operating mode...

@Auror1968 Thanks for the update. It is not supported yet and May I know the reason for the request? And I will keep attention to the similar feedback for further evaluation;

@Madaboutspurs Hi, the latest IOS APP 2.9.6 has fixed this issue already, and have you installed the latest APP?

@Oxford Thanks for the update. Have you tried to change the DNS server, like 8.8.8.8/8.8.4.4 on the Deco APP to have a look as well: https://www.tp-link.com/support/faq/1855/

@Nick_19 Hi, thank you very much for your feedback. To be more specific, were you trying to say, when trying to connect the Wi-Fi of VR400, it took almost 10mins to get an IP address from Linux...

@Fabius Hi, were you trying to say that the 3/4G backup did not fail over once the ADSL is down? And you have to restart the router or unplug and replug the 3/4G modem to restore the connection;