Can you try to login to the switch and check the status of the ports, are they in shutdown state, try make sure the cables used by port no 2 and 3 are in working conditions.
I did has a TP link switch with similar problems, the only option was to restart the switch as TP link won’t provide much management options to the switch.
You may need to considering replace the TP link switch.
Your initial issue is that you’re hookig a switch directly into a Cable/DSL modem – the modems typically only communicate with a single MAC (one device). To get your LAN working properly, install a router between the modem and switch…