wwan: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/wwan - from package: tlp

You may install the required package with command yum install {package}

Error in other languages:
wwan: bevel nie gevind nie
wwan: comandă negăsită
wwan: comando não encontrado
wwan: commande introuvable
wwan: command not found
wwan: käsku ei ole
wwan: không tìm thấy lệnh
wwan: komanda nerasta
wwan: Kommando nicht gefunden.
wwan: kommandot finns inte
wwan: komut yok
wwan: nie znaleziono polecenia
wwan: níor aimsíodh an t-ordú
wwan: no se encontró la orden
wwan: no s'ha trobat l'ordre
wwan: opdracht niet gevonden
wwan: parancs nem található
wwan: perintah tidak ditemukan
wwan: príkaz nenájdený
wwan: příkaz nenalezen
wwan: команда не найдена
wwan: командата не е открита
wwan: 命令找不到
wwan: コマンドが見つかりません