@Brickadoon Maybe you could try Huawei E3372h-320, which is mentioned in a previous firmware release note:

@Sandeep82 4TB should be working if no other compatibility issue, you could have a try.

@jmuk Only one port of the powerline adapter needs to connect your router, so if you have 4 PG2400P units, you could connect wired client devices to the remaining port of the main powerline adapter...

@fareselsokary Follow this guide for troubleshooting first: What should I do if Internet connection on my TP-Link DSL modem is unstable?

@Ahmad101 You could go to Access Management->Filter->Select Application Filter as the Filter Type Selection, but it seems that You could go to Access Management->Filter->Select Application Filter as...

@GeorKhawam Are you in router mode or AP mode? For wireless settings, try disabling smart connect and check it again.