7 Months ago I bought a Samsung Galaxy S9 and have experienced the following problems:

1. The wifi keeps dropping. An explanation mark appears next to wifi logo and wifi signal becomes unresponsive, and I have to switch off and on to get signal again. This happens x3-12 times a day. It only drops on my home router and works perfectly on other wifi routers. All other devices in home work perfectly on wifi router. It is only a problem between my S9 and my home wifi router.
2. When I listen to radio via Bluetooth through wifi, even when wifi signal hasn’t dropped, radio keeps buffering. It will go silent, but sometimes if I press power button it will play again.

If I switch off wifi, all features of phone work perfectly on 4G including radio streaming. I am guessing the settings of S9 are somehow interfering with First Media wifi router or visa versa.

I have tried the following solutions, but none of them solved the problem:

1. Reset network settings
2. Deleted wifi connection and reconnected
3. Deleted Network cache
4. Factory reset of phone, at home and at service center
5. Changed wifi settings from DHCP to static
6. Service center replaced motherboard and then entire phone, the same problem persists with new S9 replacement
7. Changed wifi channel of router
8. Changed security settings of router from WPA-PSK/WPA2-PSK (AES) to WPA2-PSK (AES)
9. My ISP said because wifi router works on other devices, the settings of S9 must be to blame

The fact that phone was replaced and problem persists, suggests it’s something to do with Samsung S9 settings.

Does anyone know a solution to this?

Thanks