ESP8266 wifi not working properly with new cellphone tethering (4G)

Factual Questions
1

I just replaced my old Huawei P8 with P30 and could not get my esp8266 work as a webserver. Esp8266 smartconfig app easily changed the two networks.

After a couple of tests, I lowered my primary phone connection from 4G to 3G…and my system worked again. Does this make any sense - wifi tethering not working with esp when phone connected to 4G+ (300mbps).

Actually I should do more testing, but one or two persons using my system may be having the same issues…So I decided to use straightdope.com rather than any esp-related forum (because these people are there).

2

You might suggest that I only received a bad phone, but I tested wifi tethering with a laptop and a tablet…

3

Major WAG: Is IPv6 turned on? Does your set up need it? A lot of such problems can be “fixed” by turning off IPv6.

4

After another test, it seems that all the surrounding wifi nets might have affected my net. Taken outdoors, everything worked as before… I think there is no reason to continue with this thread…