you can't set a DNS server on your bbox, but you can on your laptop itself.

Doesn't it help if you reset the bbox?

reset =  Hold down the reset button for 20 seconds.

Proximus
 Primary DNS-Server: 195.238.2.21 
Secondary DNS-Server: 195.238.2.22

I reset and restarted the bbox several times, but no luck

it’s a work laptop so I don’t think I have admin rights to change the DNS

seems weird to me that the proximus modem is unable to give me a decent running DNS server when connected via cable

I don’t have this problem when i connect my laptop via cable, have you another device e.g other notebook that you can connet at the bbox, to see if you have the same problem with  it?

Have you also the problem when you use wifi to connect with the work laptop

no wifi problems

the tv decoder is also connected via cable, we have drop-outs of the image or even no connexion at all “no signal” at times

a proximus employee can check your line for errors if they pick up the thread here

@M VDH What is the error you see on your screen? Is it no signal or something else? You are using a wireless connection, wifi booster or bridge, for the tv. Which one are you using?

tv and workpc are connected via cable

the network connexion remains, but no internet / tv signal at times (randomly) and returns a while later

the message is  DNS probe, no internet

FYI i dont know if it is possible te use a different DNS server on your work coputer but here is an explanation how to do it, maybe you can use the DNS server from google 8.8.8.8 to try if you get the same error → How To Change DNS Servers On Windows, Mac, iOS And Android | WhatsaByte

also an explanation of DNS probe, no internet → Fix DNS Probe Finished No Internet Error In Google Chrome - Dns_Probe_Finished_No_Internet | WhatsaByte