Could be hardware overheating perhaps.
the laptop loses the connection to my wifi. The speed goes down to 0 to 6 Mbit
What exactly happens when the connection is lost ?
Where are you measuring the speed ?
Do you mean the speeds drops from 6 to zero or drops to a value between 6 and zero ?
What do you have to do re-establish connection after it has failed ?
If the fault is reproducible, run some commands before it fails, then trigger the fault and run the same commands while in the failed state.
Check for differences in the two sets of results.
As well as before and after for
lshw -C network
Other examples of commands to try include
sudo inxi -sni
ifconfig -a
route
arp -a
If you note the time when a failure happens, checking the logs around that time might show something.
journalctl --since HH:MM
Replace the HH:MM for a value shortly before the fault.