generate network errors for testing

I would like to know. Is there any option to generate random network errors for testing of js code? I am trying to implement some error handling during the upload of files to the PHP server but "unfortunately", my internet is rather stable at home + I do it in LAN. I was trying to use a VPN switch, but it switches almost instantly, without network disruption (or at least it seems that way) and even if it worked, I do not feel like using that solution because of that frustrating routine that comes with it... Thanks!