how can i add static new ip to my server ubuntu 18

hello.
i been trying add a new ip to my ubuntu 18 server, but i can't. first i tried with netplan,after that switch to /etc/network/interfaces also, nothing works .

# ip a
--------------------
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
link/ether 00:00:d1:d0:1b:f8 brd ff:ff:ff:ff:ff:ff
inet 208.209.26.248/24 brd 208.209.26.255 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::200:d1ff:fed0:1bf8/64 scope link
valid_lft forever preferred_lft forever
3: eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc fq_codel state DOWN group default qlen 1000
link/ether 00:00:0a:d0:1b:f8 brd ff:ff:ff:ff:ff:ff

-----------
# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
default _gateway 0.0.0.0 UG 0 0 0 eth0
208.209.26.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0

--------------

i need add additional static ip:
ip - netmask - gateway
208.209.107.95 - 255.255.252.0 - 208.209.107.1

-----------------------------------------------

file: /etc/network/interfaces
-------------------
# Include files from /etc/network/interfaces.d:
source-directory /etc/network/interfaces.d
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
hwaddress ether 00:00:d1:d0:1b:f8
address 209.208.27.248
netmask 255.255.255.0
gateway 209.208.27.1
dns-nameservers 209.208.127.65 209.208.25.18

i tried:
-------------
auto eth0:1
iface eth0:1 inet static
address 208.209.107.95
netmask 255.255.252.0
gateway 208.209.107.1

not working.

2 days without finding a solution please help me.