I would send it back and ask for a new one. Because the 5G lights up for me.
If you have a 5G network SIM card, the white LED should light up constantly. At least that's how it is for me.

My home has no 4g or 5g indicator lights, even though the network is well broadcast.

The device works perfectly for me. The 5G LED display is permanently lit. The TV reception is very rarely jerky, depending on the reception at the location, of course. I tested the reception at my location in advance with my mobile via hotspot. I can also receive TV via hotspot, but then my homepods mini don't work because I don't have wifi. After testing it at my location, I can highly recommend this inexpensive 5G router. I use the data flat rate 20 from digitec (digital republic, 20.-), the SIM is included (flat rate 10).
The switch was triggered by the high fees charged by cable network operators. I now watch TV with a plan from Zattoo (20.-), which costs me three times less than before (40.-) It is important that you check your mobile phone reception at your location beforehand.