to explain more :
let's say we want to add this list of ip's:
10.10.10.160
10.10.10.161
and so on until
10.10.10.175
the default way to add it in Plesk using the mentioned OVH subnet mask
it was
10.10.10.175/28
or
10.10.10.175/255.255.255.240
this will result
so our network address that will...
just in case you came here in my same situation that you have PLESK and lot of ip's
when you add a new ip add it with that way
x.y.z.xxx/255.255.255.255
that way it will use itself when it's doing outgoing requests.
I have dedicated server from OVH, that has around 40 ip
these 40 ip's are on 3 main routing.
ip route show
default via x.y.z.254 dev eno0
a.b.c.0/24 dev eno0 proto kernel scope link src a.b.c.161
x.y.b.0/24 dev eno0 proto kernel scope link src x.y.b.74
x.y.z.0/24 dev eno0 proto...