Do you get the same speed issues on any other devices via wifi or ethernet?
You may well have a brand new PC but this can also happen if your ethernet cable is damaged or broken - to get a 100mpbs connection to an ethernet (LAN) port you only need 4 of the 8 wires (two of the four pairs, usually the orange and green ones) to achieve that, all 8 wires (4 pairs) are required for Gigabit operation in full duplex. You can also check in your operating system if the rates are set to 'auto negotiation' but they usually are by default!
Also, do you have another cable you could try? Some cheaper cables, or those provided with consoles etc, can sometimes have only 4 wires. If you're using the Cat6 cable that was supplied with your Router however, that's slightly puzzling. Make sure all connections are firm and if you have no joy, i could always attempt remote assistance to your PC to check the settings and check your Router, if permissible by virgin!
Additional, you say 10.5mb/s but do you actually mean Megabytes per second or megabits? If you're getting 10.5 Megabytes per second I'm going to assume you have the 100M service? If so, that's within spec for the package 🙂
Ill give the cable a go as i am using the sMe one thats been there for years so could just be a simple fix,
Yes i am on the 100M service but i used to get faster dl speeds on that one than i do from the new one wifi dl speeds are amazing speed test also show over 100mb/s dont know if ever one is the same these days but i am also full fiber all the way though as my area recently had virgin installed.
Thank you for reaching out to us in our community and welcome, sorry to hear your download speeds have dropped, I have had a look our end and can see some issues and your SNR levels are out, looking at things it does point to your connections.
Can you check all your internal connection including any splitters are hand tight, try unscrewing and putting back on again to make sure correct, once done also unplug the Router from the power leave 2 minutes then plug back in.