I need help with my new netplugs.  My new TP-link extender (both the same), the wifi cuts out and speeds are not consistent anymore after 2 weeks from purchase.  My downstairs router with Virgin Media gives 300 Mbps download, 30 Mbps upload via WIFI.  Upstairs is total WIFI dead zone with netplugs.  i upgrading my netplugs to TP-Link WPA4220 with 2 extenders.  Initially after setup got speeds of 30 Mbps down, 30 Mbps up which is very good compared to the old Solwise plugs. But after 2 weeks the performance of the WIFI is now terrible- the WIFI keeps cutting out, speeds not consistent, at times no WIFI yet via ethernet cable always excellent?  2 weeks ago I could watch 4k tv (ethernet) and use the internet via WIFI on my iphone all through the extender at the same time without issues.  Now when I use a broadband speed app, the downloads range from 30 to 0.5, uploads sometimes no connection.  Why has the performance deteriorated?  I have reset, re-installed, done everything to fix it but can't.  Note the speeds via ethernet from extender is always fast at 60Mbps consistently, just the WIFI problem.