New wifi router - can't upload...

We have two machines: an xp pc and a chromebook. We used to have a router which connected to a wireless router that was set up as an access point. The two machines connected to that and used the internet flawlessly.

But things changed.. First router in the line got ditched and the other wireless router was bricked, so we got a new one. Then the problems started....

The chromebook (my guess) had it's connection set up anew.. and it works flawlessly.
The xp machine however, used the same connection settings as it had before...

It can browse the internet fine.. it can connect ftp fine and browse folders (using filezilla)....
However... it cannot upload files through ftp, nor http.. and when I run a speed test in google, I get a "network error" when it comes to the part where it tests the upload speed.

So my guess is.. that the "wifi connection settings" on the xp machine aren't correct (maybe due because of the fact that it's not an "access point" anymore...?).

Anyway.. I am used to work with pc's (from the dos era up to windows 10), so I'm not a complete greenie, but my knowledge of the wifi settings are pretty rusty. Does anyone here know what I should do? Set up the wifi connection anew and if so, what should I look for/check for? (is there a manual somewhere that tells you step-by-step how to set this up?)

Any help would be welcome!

Thanks!

 

can you give me make and model of the new wireless router and if possible a more exact wording of the error message, and if there are any errors in event viewer pertinent to this issue, then I need the source and event id number and any file name or .dll that may or may not be listed