Why Skype cannot login through its software in Win8?

When you say through web, is it Chrome or Firefox etc. These browsers allow for proxy settings that bypass system proxy setting.
Please check your system proxy settings

Thanks for your reply. I can login Skype via Chrome browsers, but cannot login via Skype(please see first picture attached)

Do you think I need to change port? Please see second picture attached
second-picture.PNG

Windows Firewall or 3rd party Firewall ?

No, leave port as is. Please provide system proxy settings

I attached third picture. Please see it. Is this correct info you want me to show?
third-picture.PNG

If you are using Windows 8, not Windows 8.1, you need to update Skype client from the link below.

https://www.skype.com/en/download-skype/skype-for-windows/

If you are using Windows 8 or Windows 8,1, you can install the Skype app from the link below.

https://www.microsoft.com/en-us/store/p/skype/9wzdncrfj364

my Win is version 8.1
what is difference of the Skype between your link and the below link that i used to download?
 http://www.skype.com/go/getskype-full
thanks

Are you using Skype for Desktop or the one from Store? The one from Store is crap. I always remove it and install one for Desktop directly from Skype.com

Your link is to download offline installer for Skype client.

Try to do windows update to see whether it fixes the problem. The offline installer for Skype client seems to have a problem with win 10 (maybe win 8 also) which can be fixed by windows update.

https://community.skype.com/t5/Windows-desktop-client/Trying-to-run-skype-7-34-103-get-error-MSVCP140-dll-Error-status/td-p/4649230

@noxcho,
I do not know your question.  Can you explain it in detail? can you send me the link for download?

Are you using Skype for Desktop or the one from Store?

@Jackie Man,
this link is for download full size Skype in my pc. it is 56.641mb。 and i also updated windows. but it still cannot resolve the problem

Thank you.  solved. it missed a file.