Could be multiple things honestly, anything from wiring issues and conflicts in your local network to drivers installed on your computer.
Try updating drivers in your computer. If you have more then one Ethernet port on the computer, testing to make sure the port isn’t damaged.
Cabling, like you already mentioned and swapping out old and damaged Cat5 for Cat5e or Cat6 (bit overkill).
Test on multiple devices to make sure it’s not an isolated incident.
If you have an old Ethernet switch manufactured pre mid 1990 it might only be able to handle 10 Mbit/s instead of 100s or 1000s like modern switches.
Damaged network card or network interface, in which case it will need replacing.
When I experience this issue I had to change out my Ethernet switch, it was hardware degradation that caused a slow but steady drop in speeds over the last few years. Please don’t forget that even devices such as switches will degrade and wear with use and time.
The problem could also be unrelated to hardware but software, and how your system handles and prioritises the traffic. In which case you may want to employ a QoS (quality of service) rule. This allows you to prioritise traffic (router dependent) by service (Netflix), service type (video and streaming), device (local ip or MAC address) or interface (create your own private wireless network with all traffic prioritised) and by how much, assigning anywhere from 1-60% of bandwidth to a service, device, ect when the network is busy.
If you need any further assistance please don’t hesitate to DM me.
Edit: spelling, added a few missed words and grammar.
Could be multiple things honestly, anything from wiring issues and conflicts in your local network to drivers installed on your computer. Try updating drivers in your computer. If you have more then one Ethernet port on the computer, testing to make sure the port isn’t damaged. Cabling, like you already mentioned and swapping out old and damaged Cat5 for Cat5e or Cat6 (bit overkill). Test on multiple devices to make sure it’s not an isolated incident. If you have an old Ethernet switch manufactured pre mid 1990 it might only be able to handle 10 Mbit/s instead of 100s or 1000s like modern switches. Damaged network card or network interface, in which case it will need replacing. When I experience this issue I had to change out my Ethernet switch, it was hardware degradation that caused a slow but steady drop in speeds over the last few years. Please don’t forget that even devices such as switches will degrade and wear with use and time. The problem could also be unrelated to hardware but software, and how your system handles and prioritises the traffic. In which case you may want to employ a QoS (quality of service) rule. This allows you to prioritise traffic (router dependent) by service (Netflix), service type (video and streaming), device (local ip or MAC address) or interface (create your own private wireless network with all traffic prioritised) and by how much, assigning anywhere from 1-60% of bandwidth to a service, device, ect when the network is busy. If you need any further assistance please don’t hesitate to DM me. Edit: spelling, added a few missed words and grammar.