Try a VPN on the phone.
You wrote about the DNS but didn't tell enough. Which IPv4 and IPv6 DNS did you use?
I’ve been having a problem lately with WIFI use. Mostly, everything works fine, just as it did in the past. However, lately I have gotten some odd problems on mobile devices but not on computers:
• email clients (Samsung email, gmail) do not work properly. They do not synch up and most of the time messages stay in the outbox and do not send. Once in a while, the messages do send, but hardly ever. I have tried to reinstall these apps and re-add the accounts, but it makes no difference. (I can use email on mobile through the browser OK, but not through any app.)
• Twitter and Facebook and Pinterest media loads very slowly or not at all. For example, if I click a video, it often takes about 20 seconds to start, or it doesn’t start at all. As well, some avatars don’t load for people.
These problems on mobile devices go away when I disconnect from wifi and just use mobile data. Also, my computers and ps4 work fine on wifi.
I thought it might be an issue with my phone, so I did a factory reset, but the problem remains – and it exists with other phones too. My router firmware (for an Archer C7) is up to date. I have also done slow reboots of the modem and router, but it makes no difference. I am a bit hesitant to do a full reset of the modem, because I do not have the technical ability to update the firmware after.
My ISP thought my problems might be because the IP I had been assigned had recently changed. They told me to do a MAC-clone so that I could get a new IP on a different subnet. However, I was still assigned an IP on the same subnet and the problem persisted. They also tried to get me to try changing some DNS settings on the router settings, but nothing worked.
What do you think is likely the culprit here?
a) Faulty modem?
b) Faulter router?
c) Another problem?
Thank you for your time.