Unable to connect

[nemo1985]

Hello everybody.
For some years I used a home computer as limp server with debian, everything worked like a charme.
Today I started the computer after a couple of years and it suddenly can't connect to the net.
My router doesn't detect it, I have always used a static ip (with ip rservation for the mac address in the router).
I messed with it for some hours, did the net configuration from scratch but it just doesn't work.
I tried to run ubuntu from a usb drive and the network works without issues.

route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.0.1 0.0.0.0 UG 0 0 0 eth0
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0

ip route show
default via 192.168.0.1 dev eth0
192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.3

ifconfig
eth0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 192.168.0.3 netmask 255.255.255.0 broadcast 192.168.0.255
ether 00:19:66:8e:65:fa txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback)
RX packets 888 bytes 115929 (113.2 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 888 bytes 115929 (113.2 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

this is my interfaces file:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
allow-hotplug eth0
iface eth0 inet static
address 192.168.0.3
netmask 255.255.255.0
gateway 192.168.0.1
# dns-nameservers 192.168.0.1 8.8.8.8

I suspect that the problem is the missing gateway (which should be 192.168.0.1).

Thank you in advance for any help you can give me.

[bijayalaxmi1808]

I think yes gateway is needed when you refer to an IP which is outside of the local network.
This is the case when you request something that is on internet.

I am not sure if the DNS server is also needs to be added or not?