Wrt3200acm + rtf3505vw + buffalo ls-wxl webaccess

[JFR]

Good afternoon

I have recently installed fiber optics in my house and they have supplied me with this router mod: RTF3505VW from the internet provider
I have attached a structure image of my devices, the WRT3200ACM I have it with the official firmware seems to me more beautiful let's say it, but I do not know if it is more advisable to install a ddwrt or an openwrt I have seen comments on vulnerabilities of this router and as they are years I do not know if they have been corrected with the latest firmware (FW_WRT3200ACM_1.0.6.186168_prod) I would appreciate someone throwing light on this. the fact is that I can not access the service provided by my NAS Buffalo the WebAccess I tried to open ports but without success I would appreciate any recommendation thanks

[JFR]

the previous thing was a false positive I was connected to the LAN without realizing it and that's why I let myself connect
I could only make it work by activating the DMZ over the ip of the NAS on the WRT3200ACM router

[JFR]

Good Morning
Yesterday I got to thinking, if it works with DMZ it has to work through noses with some port and calmly deactivate the DMZ, then verify that it no longer connects, I proceeded to open the port and everything worked perfectly access to the WebAccess without problems