Hi there mehrpour ,
Welcome to the community,
Upon checking the status and quality of your service it all tests are passing in the NBN portal.
I recommend that you peruse the useful links i have attached in relation to resolving slow speeds.
For helpful tips on how to improve your internet speed, follow our guide at
I have also attatched these following links in releation to troubleshooting possible issues with WIFI
give this a try and let me know how you go.