When I connect to a 4G network, I keep getting an intermittent Error 400.

My ISP claims one of the following:

* A machine problem (I tell them it happens on all machines)
* A router issue (I tell them it happens when I connect directly to the dongle I'm using)
* Geographical coverage! It happens in many places, but not as recurring as it is in my current location

Questions:

* How true is that?
* Can location cause this specific Error 400?
* What can I do to fix that locally if at all possible?
* What can I tell my ISP technical care to help them figure it out (When they tried the dongle on their machine, it did not fire any errors!)

Note: I get that error on all browsers, and I got it on all systems (Windows 8, Windows 10, Android's Chrome), but I cannot confirm yet if I get any of that on Skype, WhatsApp, or other services that use the internet). 

> 
> **Also note: I have other providers, when I switch to those other providers, I get no issues.**
> 
> 
> 

I use no proxy servers.

**Extra:**

Here is an example of what I get on fiddler:
326 The Server did not return properly formatted HTTP Headers. HTTP headers
should be terminated with CRLFCRLF. These were terminated with LFLF.

**Extra:**

One website was generous to give me the following error message upon a 400 error, does it mean anything?

[![Error 400 Details](https://i.stack.imgur.com/9p8ql.png)](https://i.stack.imgur.com/9p8ql.png)