Nas on modem ISP modem, PCS on TPLink M5 with different subnet. Can't access NAS with pc (in file explorer)

Plugged the NAS on ISP modem intead of the TPLink Deco M9 because then I can forward the port and access some apps via web. But I loose the ability to access the NAS with SMB under windows.

NAS in on 192.168.0.xx and PC, connected to TpLink M9 are on 192.168.68.XX

How can I get both things (outside access and SMS file explorer).