In short, my phone cannot connect to the internet via 2 WiFi access points in my house. 4G mobile data works fine. Connecting to other WiFi and hot-spots away from my own WAN works fine.
All other devices, around 14 which includes phones, laptops, PC's, servers, VM's and 2 chromecast devices, all work without any issues.
My mobile phone worked fine until sometime late Friday afternoon. I did not install any new software or fiddled with the settings in days. Phone works well no issues with anything.
Mobile Phone - Doogee N10 - about 1 year old on Android 8.1.0
Router WiFi AP 1 - TP-Link Archer VR1600v IP 192.168.1.1 WAN connection
WiFi AP 2 - Netgear R6020 IP 192.168.1.178 (reserved)
LAN to LAN connection between the TP-Link and the Netgear Routers.
Netgear Router WAN port is disabled.
DHCP runs on the TP-Link Router LAN IP Range via DHCP 192.168.1.100 - 192.168.1.200 /24
Test 1 : 4G mobile data enabled / WiFi disabled - internet access OK from all apps.
Test 2 : Switch WiFi on for AP 1 (TP-Link) - establish link, gets IP does not report internet access problem. - But all apps don't connect to internet, browser times out.
Test 3 : Switch WiFi on for AP 2 (Netgear) - Result same as test 2 - No internet connection.
Test 4 : Get another member of the household to switch on WiFi hotspot on their mobile phone - Connects and internet works fine on all browsers and apps.
Things I have done to check out possible issues:
Assigned a reserved IP of 192.168.1.177 on the DHCP in case of aduplicate IP from another device.
Checked firewalls and black lists and filters on both routers, nothing. I can see the connected Doogee mobile phone in the WiFi connected listings same as all other devices.
Rebooted, powered down and deleted all the WiFi networks settings one by one made no difference.
On the Doogee Android admin menus, there is an option to completely reset all the networking configuration settings to factory. Done, re-entered all the settings and made no difference.
On my PC (Linux), I have 2 terminal sessions open. On the 1st one I ping a random ftp site somewhere on another continent. Ping is stable at about 500ms. This is my confirmation that there are no issues with the WAN connection. On the seconds terminal, I ping the Doogee Mobile phone on the 192.168.1.177 IP.
Phone connected to AP 1, it often stops randomly with no ping activity, and then just carries on normally after some time.
Phone connected to AP 2 pings seems better without long ping pauses.
Switching between AP 1 and AP 2:
3.1 AP 1 - When switching to AP, it can take up to a minute before the ping responds.
3.2 AP 2 - Ping resumes as soon as a connection to AP 2 is established.
Pinging the Doogee is all over the place. Ping times vary anywhere from 2ms to around 700ms.
I don't have any side loaded apps installed. Everything is from Google Play. I installed Trend Micro mobile AV briefly just to make sure it is not something that the Play store didn't pickup.
I can from the browser on my phone connect to any other server / router on my LAN. I can connect to both the routers management interfaces. I can use my "Fing" app to browse all the devices on the network, port scan them and ping them from my phone. Fing however sometimes reports that I do not have internet access, but not all the time.
It seems like my phone refuses to connect to the internet via my WAN port. All other devices have no issues via the same WAN port. My phone connects to the internet via all other means except the WAN port on my network. No firewall or blacklist preventing it. No duplicate IP's.
I am completely baffled, any ideas or pointer welcome please :)