Bash script check if user-input matches certain form

Below you can see my bash script

#createSession.sh

echo "Welcome to ADS2 Session Start..."

while [ true ]
do
echo "Starting service Daemon on the targert"
echo "Enter the ip-address of the target"
read x
if [ -z "$x" ]
then 
    echo "ip-address is empty"
else
    echo "Connecting with target..."
    if [[ $x =~ ^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$ ]]
    then
        ssh nvidia@"$x" "/opt/ads2/arm-linux64/bin/ads2 svcd&"
        echo "connection succeded"
        break
    else
        "Make sure the io address in the coorect form"  
    fi

fi
done

echo "Starting service Daemon on the host"
ads2 api system;
ads2 cls create;
ads2 ses;
echo "session created"

First question

As you see, the script checks if the user input machtes the ip-address form. However, i would like the script to also accept the ip address as a string which has this form fdt-c-agx-4arbitrary numbers. The last part of the string can be any arbitrary 4 numbers. As a result, the if statement be like

if [[ $x =~ ^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$ ]] || [ $x = #machtes fdt-c-agx-4arbitrary digits]

Second question

The ip address could be entered in the right form, however does not exist. Consequently, the ssh returns in this case ssh connection time out. However the string connection succeded will be printed which is not true. So how can i make the scripts enough clever to realize that the connection in this case is not established?

Thnaks in advance