If your having problems with connection and you have tried 2 different FW versions, means there is a different area that you need to look either at the ISP modem or something in your configuration settings isn't set up right.
One way to check is to test directly with the ISP modem and the PS. Does the problem exhibit there?
My A2 came loaded with v1.21 and works just as good as my A1 loaded withh 1.22. Others are using 1.23 as well.
Maybe someone can review your router settings with you using
teamviewer.