Nmap/netdiscover mac adress and vendor/devices not showing

Question

Pls first of all when i login into linux the wifi and ehternet are connected but the internet doesn't work (firefox displays error) unless i disconnect or shutdown eth0 , after that i want to scan all devices that are connected to my network I type netdiscover -r 192.168.1.0/24 Or i try all the combinations 192.168.11/24 But the scan only shows 1 or 2 mac adresses with unknown devices and vendor's name so basically it doesn't scan my house's network devices ifairly think it scans only my ethernet or local network of my pcs pls i need help i been trying for two days and no result and im beginning to lose hope i just want the scans to be normal and show all the devices and my network l device type snd vendor and also fix the internet while all the interfaces are working (eth0 lo0 wlan 0 ) plus a new added which is a docker0 anyways pls need help I type netdiscover -r 192.168.1.0/24 Or i try all the combinations 192.168.11/24 But the scan only shows 1 or 2 mac adresses with unknown devices and vendor's name so basically it doesn't scan my house's network devices ifairly think it scans only my ethernet or local network of my pcs pls i need help i been trying for two days and no result and im beginning to lose hope i just want the scans to be normal and show all the devices and my network and also fix the internet while all the interfaces are working (eth0 lo0 wlan 0 ) plus a new added which is a docker0 anyways pls need help