Hi , I suggest first try connecting using the non-wifi ethernet cable option , after turning off the wifi network device .

if the problem remains then maybe an isp issue and if connects as expected then possibly to many wifi devices connected ( known and possibly unknown devices )

Being previously owned the computer may be registered on an isp subscription database  to another network modem or router and so the isp is questioning the connection, a phone call to your isp to confirm your ownership should resolve this issue

Network wifi devices usually support only limited connected devices - i think mine is 6 or 8 - so if more devices than maximum have connected , your connection will be problematic for obvious reasons. Try to access your modem control panel and note number of connections

in future this may assist communications

https://translate.google.com.au

ps - unless a tech issue is absolutely a specific manufacturer problem is best not to mention the manufacturer name , as they tend to get a bit excited from the unwanted publicity  within a retail / private line item auction hosted forum , and also many tech people may not reply if the manufacturer name is noted.

Just a thought , welcome to Australia