no wireless connect with ath9k

[cyrano de bergerac]

after upgrade from 14.04 to 16.04, i have no wireless connect.
I get a correct ip, dns, and gateway entry from the router. no erros in the syslog and kernel.log.
ARP request works fine, but icmp failed. i can't ping my own router.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubuntu-release-upgrader-core 1:16.04.14
ProcVersionSignature: Ubuntu 4.4.0-22.40-generic 4.4.8
Uname: Linux 4.4.0-22-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CrashDB: ubuntu
Date: Sun May 29 15:01:43 2016
InstallationDate: Installed on 2016-05-26 (2 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=de_DE
 TERM=xterm-256color
 PATH=(custom, no user)
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntu-release-upgrader
Symptom: release-upgrade
UpgradeStatus: No upgrade log present (probably fresh install)