You can choose your ISP firstly. Then consult the dialup way of your ISP. TP-LINK generally support PPPoE, dynamic IP and static IP.

@Jan_Kab For the problem that loss internet, did your PC has IP address at that time? If not, maybe you can try to set up static IP address even static ARP, check if can solve the problem. For the...

As we talk in another post, if you use link backup. The backup WAN (your WAN2) will be disconnected unless primary WAN down. It's only for backup so will not work all the time.

@Yos Do you mean "optimized routing" ? With Application Optimized Routing enabled, the router will consider the source IP address and destination IP address (or destination port) of the packets as a...

If your ISP just provide the Ethernet cable to you and your tp-link router supports the dialup way that your ISP uses, then the tp-link router can replace the ISP router. And VPN settings would be...

'Reset' means to go back to factory default settings. So you must loss configuration.