are you sure it isnt the device? I know with mine for a while now if I've had tabs opened or a process is stuck open such as chrome it can hog resources and slow things right down on the device itself
If you mean by device, the computer? Yes, I can confirm that all the devices simultaneously will not be able to make any new connections.
The MTR test would the all indicate that there is no response from after the tower will all packet dropped.
Strangely enough, if you had a stream going, it would not be interrupted. EG streaming brianfm, zooming or teams call would just continue, but you can not initiate a new connection, such as a new webpage, new call, new meeting etc.