Question After connecting new computer to our network, internet is on and off.

[GnBnCn]

HI, I purchased a refurbished computer from Amazon. : Dell Vostro 3800 Desktop Computer, Intel Quad Core i7-4770 up to 3.9GHz, 16G DDR3, 512G SSD, DVDRW, WiFi, Bluetooth, HDMI, VGA, Keyboard, Mouse, Win10 Pro 64


After I connected the computer to our network, our internet became unstable: some time all computers loose internet connection, and come back later.

I think there might be ip conflict, or conflict from bluetooth. However I’m not too sure.

Please let me know how to know what cause the issue, and how to fix it



Thank you.

 

[Krotow]

Or same MAC addresses in subnet

 

[GnBnCn]

Or same MAC addresses in subnet

Is it possible to have same MAC address??
The odd might be less than Lotto.

 

[rgd1101]

change the ip address?
did you do a fresh os install?

 

[GnBnCn]

change the ip address?
did you do a fresh os install?

I think I use DHCP.
So I just connected the computer without doing anything.
I didn't do fresh os install yet.
I just used the computer as I got it from Amazon.

 

[rgd1101]

did you check for malware before connecting to your network?

 

[GnBnCn]

did you check for malware before connecting to your network?

No I didn't.
I don't think Amazon seller installed malware.
However I can check.