Help me, please

Until some time ago I happily used my WD EX2 by connecting it via a TpLink router to a Marantz NA2007.

Recently my internet provider has changed my line by switching to fiber optics and replacing the router with a Huawei HG6245D.

From that moment the Marantz no longer sees the audio files contained in the EX2. Same thing for the Samsung Smart TV.
Even if I try to access via Hi-Fi Cast from mobile, the app cannot find any UPnP / DNLA device active (showing the previous EX2 configuration as offline).
At the same time all the files are perfectly visible and editable from the computer (Windows 10).

I tried to do a system restore of the EX2, but without any benefit.

My media files reside on 2 shares (MUSIC and MOVIES) both configured Public ON, Media Serving ON, Oplocks ON, NFS Access ON.

Can anyone help me solve the problem?