Dell xps 15 9560 WiFi problem (ping spikes)

So I have had this laptop for some years and never had any issue. A couple weeks ago it started to create problems on the WiFi network (private network): speed and ping are all good, but every 5 to 10 seconds (not precisely), it causes lag spikes up to 1000 ms for a really short time, basically crashing, then back to normal.
This problem occurs only on this laptop, but seems to create issues with other devices too, only when this one is connected. I am about sure that it's not the network per se so I can't really call the ISP to get help.
Other then lag spikes seen through ping test, i can notice that in the modem page related to the radio channel there is a ton of data sent to the router when ping spikes occur, like 10 times more than the normal usage shows; however using other nets with this very same device works totally fine.

Already tried:
-verified ping to various nodes, the problem seems to persist on the laptop-router interval.
-updated drivers, windows and all i could think of.
-searched in event viewer (not an expert though), but found no hints
-searched in task manager->network, usage doesn't go up when spikes are present
-did some other things i could find online, like ip setting turned off through cmd, but had no results
-checked on router's page (Fritz!Box), but found 0 signals of blocks (i am the only user who ever opened that page, no one else knows how to do it so i'm pretty sure there isn't anything on that side)
-ran AVG and MalwareBytes, nothing suspicious found
-other Wi-Fi works totally fine

Lately, I also had some problems with the video settings while online gaming, with fps staying at a good 60 but suddenly the game seem to stop intermittenly (mouse still goes without any issue), although I'm not sure that's related to the bigger issue here.

I am at a blank point, any help is REALLY welcome.
Thank you