Phone connects to Wi-Fi but no internet

CaVes

I bought a pack of three AC2100. Installation went smooth. I now have excellent connection to my Chromecast (4th generation) and I'm able to stream 4K material with Dolby Atmos. I can see that my TV is connected to the Wi-Fi. I can access my Hue Bridge and my JBL Soundbar. 

But for some reason my phone when connected to the Wi-Fi, it gives an error saying there is no internet connection for the Wi-Fi - "Connected (no internet connection)". This first happened about 30 min after first setup. I have reset all and started setup over. No change in error. 

Is it a problem related to the AC2100? Or perhaps my internet provider. I have a 500/500 connection. 

CaVes

I should point out that its a problem for both phones in the house hold, Huawei P30 Pro and P20. 

Pixel

It looks like the Multy works fine. but somehow the Huawei mobile is not working.

If you other type of mobile, you can cross check if the symptom would occur on other mobile or only happen on Huawei.