There is no firmware to update on the model page:
https://www.tp-link.com/br/support/download/archer-c50-(w)

other firmwares give error: 4503

This problem happens with two routers that I bought

Does anyone know if there is an update for it?

There is some pppoe configuration that makes it crash like this? it only comes back when it restarts.

Sometimes, even after restarting, it freezes and doesn't want to come back.