Could you father children while being on TRT? I have heard that there is a chance that you can become infertile while on it, and after you quit, there is a chance that your "system" does not start up again.
Yes, TRT doesn't make you sterile. But it likely lowers the quality of your sperm. There is a small chance of becoming infertile and there's a small chance your system won't start up again if you decide to stop. Generally though, for people that have naturally low levels and are on TRT, they wouldn't want to stop and return to those levels after experiencing life at normal/high levels.