Reason for a slow download speed?

We have a 250k line in the house. A computer shows the values during a speed test. When I do the speed test, I only get 90k download but the same upload. Both are on the LAN. I connected my cable to a laptop and it got the 250k values. Drivers are updated with me and I once had the 250k values. Antivirus and firewall deactivated make no difference. Now I don't know where to look anymore.

It may be that the network card in the computer can't process such high speeds because it is too old.

Dear user,

Maybe your cable or network adapter is damaged?

Maybe the LAN cable is not correct:

It shouldn't be too long and it should be a CAT5e.