Sound Quality and WiFi (Chord Mojo/Poly + Roon / Glider)

Dear Roon Community,
I am new to Roon and seek your advice regarding sound quality and WiFi.

First of all my Setup:

  1. NUC8i7BEH [ROCK Rune Core]
  • 2x 16GB Crucial 2400 DDR4
  • Transcend PCIe M.2 SSD (2280) 512GB [OS]
  • Crucial MX500 2TB (SSD) [Library]
  • Acopian Linear Power Supply 12V 70Watt
  1. Netgear GS108E Switch
  2. Ethernet Cables are Cat. 6A
  3. Remotes are Ipad Air 2 and iPhone XS
  4. Endpoint is Chord Mojo/Poly with Sony IER-Z1R

Currently the Core is connected via Ethernet to the switch which is connected to the Router. The Router is a Aterm Series from the Japanese company EO Hikari (I live in Japan). The sources are Wave files on the internal storage and a Tidal HiFi subscription.
Alternatively Wave files on the Poly SD card (Glider App).

I truly love the Roon interface, its background information, search function and speed.
However, yesterday evening I was listening to my Music over Roon and felt like it sounds somehow thin and distant. Having that impression I switched to the Glider App which was my to go to before Roon and was shocked. The difference in sound quality was huge, at first I though it is only for the files on SD Cards but then I started comparing Tidal over Roon and over Glider. Even there is a clear difference. Glider sounded significantly better.
This puzzles me a lot as I really would like to go with Roon as it is so convenient. I even ordered a Naim Mu-so Qb2 for its Roon readiness.
The thing that Puzzles me most is that Tidal should not sound so different as in Both cases the Data is streamed wireless.
The current situation has affected my confidence in Roon quite a lot and I have still 7 days left to revoke my lifetime subscription. Any fast solution would be most appreciated.

What can I do to improve the sound quality of Roon?

I have been thinking of going wireless only with the core, however, also the the NUCs WiFi is activated in the bios it does not appear in the Web GUI of ROCK. I only have the tab for Ethernet there.

Any help, tips or insight is highly appreciated.