Unable to connect to some Mobile apps on my Android phones through WLAN

[umedhah]

I have 

Nighthawk AX5 5-Stream AX4200 WiFi Router (RAX43)

ever since i had the router I am unable to sync to certain apps such as WhatssApp Outlook etc on my phone. I have to use a VPN connection to sync those apps.Phone is a Galaxy Note20 ultra. Also i have another Anroid if the phone is on standby it doesnt get any notifications from WhatsApp Viber etc. If i try other WLANs or use Mob data then works fine. 

I have reset the router tried differenct WAP settings too.. Still no luck

[FURRYe38]

What Firmware version is currently loaded?
What is the Mfr and model# of the Internet Service Providers modem/ONT the NG router is connected too?

[umedhah]

Hey thanks for the reply. Im using V1.0.2.82. 

I cant find any info in ONT. I can tell you is.. it is called Chrous Gateway - and i am in New Zealand.. ISP is Spark NZ if helps. 

Thanks again. 

[FURRYe38]

Usaually if a modem or ONT says "Gateway", then some times, this means there is a built in router at this point. Having two routers on the same line can cause problems. This would be a double NAT condition which isn't recommended. https://kb.netgear.com/30186/What-is-Double-NAT
https://kb.netgear.com/30187/How-to-fix-issues-with-Double-NAT
Couple of options,
1. Configure the modem for transparent bridge or modem only mode. Then use the NG router in router mode. You'll need to contact the ISP for help and information in regards to the modem being bridged correctly.
2. If you can't bridge the modem, disable ALL wifi radios on the modem, configure the modems DMZ/ExposedHost or IP Pass-Through for the IP address the NG router gets from the modem.
3. Or disable all wifi radios on the modem and connect the NG router to the modem, LAN to LAN configure AP mode on the NG router. 

I'd contact your ISP to see whats at the ONT. If there is a router here, ask the ISP to help you bridge the ONT or disable the router feature at the ONT would be first option. If not, try option #2 from above.

[umedhah]

Cheers ill have a chat to ISP to ensure what the model and make on my ONT. If its actual a Gateway.. if so what the next steps are going to be. Previously I had a Huawei HG659b. I had no issues. 

[FURRYe38]

The suggestions are provided for next steps...if the ISP can get your condition to a signal NAT condition, then your apps should start working. 

[umedhah]

Sure will do.. In the mean time i tried a DLink Router and worked fine without me having to conenct to VPN on my devices. Thats surprising.