How can I monitor my TP-link Router's traffic and bandwidth which does not support SNMP protocol?

Hello

This depends on whether the router you want to monitor supports protocols that PRTG uses, it doesn't have to be SNMP, but there needs to be some way for PRTG to get that data.

PRTG also support Flow and other types of bandwidth monitoring, ultimately there has to be some metric that PRTG can query for that to work. Please see this list of supported bandwidth sensors.

You can check if there are alternative firmware images for the router that would then support SNMP, please be aware that this is something you'd perform at own risk and we can't assist you in that as is will probably also void the device's warranty.

Most enterprise-grade devices will support SNMP by default.

The list of all available sensors can be found at https://www.paessler.com/manuals/prtg/available_sensor_types.htm

If there is only a single device connected to the router, you could monitor the traffic of the local network interface, as long there is only one device connected to the router, the values should match the values of WAN utilization.

If you have a managed switch there is a workaround for this.

Plug all you interfaces from the router into a managed switch. Create a vlan for each of these interfaces and put the other connection into this same vlan in the same manner. This is also handy if you need to do remote cable changes after hours, makes it much easier to do.