Why the WiFi works only with USB WiFi dongle, not with the laptop on-board WiFi?

I have a Fritzbox wifi router, and the wifi network name never(almost) shows up in the laptop. So I mostly use LAN cable. Very rarely, I have been able to connect to the wifi network with my laptop(probably twice in this year). It is extremely random. I tried changing the wifi channel in router to something less than 11, and it did not work. Also, I checked that the router is not blacklisting my laptop. **I *can* connect to other WiFi networks, *but not* with fritzbox routers.** However, I can connect to the same wifi network, if I use a wifi dongle. Why is that the case? And how can I use my on-board laptop wifi? Some of the device details using ifconfig: **Laptop:** Centrino Wireless-N 2230 logical name: wlp2s0 version: c4 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=iwlwifi driverversion=5.4.0-150-generic firmware=18.168.6.1 latency=0 link=no multicast=yes wireless=IEEE 802.11 **Wifi-dongle**: LogiLink Wireless N150 logical name: wlx7cdd90913071 capabilities: ethernet physical wireless configuration: broadcast=yes driver=rt2800usb driverversion=5.4.0-150-generic firmware=0.36 link=yes multicast=yes wireless=IEEE 802.11