Automatic detection of default gateway is wrong

I'm ruing Debian Jessie on RPi3 (Raspbian). The network coection is on wlan0. Usually, after filling the wpa_supplicant.conf fields, rebooting the network services leads to a working Inteet coection.

On my machine I caot reach anything outside the router because a wrong default gateway.

After a reboot this is my route -n output:

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.178.1   0.0.0.0         UG    0      0        0 eth0
192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 wlan0
192.168.178.0   0.0.0.0         255.255.255.0   U     0      0        0 eth0

but the gateway is 192.168.1.254. In fact if I type:

route add default gw 192.168.1.254 wlan0

this is the new routing table:

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.1.254   0.0.0.0         UG    0      0        0 wlan0
0.0.0.0         192.168.178.1   0.0.0.0         UG    0      0        0 eth0
192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 wlan0
192.168.178.0   0.0.0.0         255.255.255.0   U     0      0        0 eth0

and the Inteet coection is now working. I never needed to manually set the default gateway.

Perhaps I need any other service?