Can a Change in Landscape Affect an Infill Mast's Signal?

[Konvex]

I live in a remote area, and my house is served by an infill mast. This has allowed me to connect fine for around six months using my sim through a router. Also, my mobile phone works no problem and so does my mother’s mobile phone.

There has been a lot of tree felling going on in the valley around the mast these days, and I’m wondering if this can affect a mast’s signal?

A neighbour that lives on the other side of the mast has repeatedly said she has had an issue where the mast will not allow her to connect using her EE phone – neither for calls or the net. She’s been in contact with EE a lot about it – nobody knows what the reason is.

My router SIM simply stopped working one morning and would not allow me to connect. It shows bars on the router, but it wouldn’t connect. So, I took this SIM out and put it in my phone – still nothing – no calls or internet.

I have since tested the router with my mobile phone SIM – it works no problem. I have tested the bad SIM in a different router – it doesn’t connect. So, the conclusion is categorically that this SIM has an issue with connecting, and it isn’t a hardware problem.

So, I took the bad sim and put it in my mobile phone and drove along the road until I was on the other side of the mobile mast… it then connected! I continued on for miles until I was out of range of this mast and onto a different mast – again, connects no problem. I drove back until I was again in range of the original mast but approaching it from the opposite side to my house – it connects. I travel past the mast towards my house and it still connects. I get back into my house, and the sim still connects. I then switch the phone on and off to check… it still works.

However, I then put the SIM back in the router and it has the same problem again – no connection. I take the sim out and put it back in my phone… it doesn’t work! It seems that after a small amount of time on this side of the mast, it stops working!

So, you can see, that there is some issue with this infill mast and the proximity of connection to it. This is backed up by the issue my neighbour also had on her side of the mast.

The only thing that has changed recently is the tree felling in the valley. Could this possibly be the cause of these strange issues? And if so, does the mast “recalibrate” itself after a while to accommodate this change in landscape in some way?

One flaw in this theory is, that my other SIM has been working fine, so why would only one SIM be affected in this way?

Thanks for any advice 🙂

[bristolian]

At the top of the tower, there will very likely be 3 sets of antenna, each covering (in most cases) a 120degree "sector", so some of your issues could be explained by there being an issue with one sector.

The tree felling - this would, if anything, increase the coverage footprint as there's less impedance to RF in free-space. There may be coverage optimisation ongoing, but this would be to improve the overall service.

Issues with particular devices not connecting in rural areas can often be due to low-band "extended range" 800Mhz coverage being used, this relies on either a VoLTE/4G-calling compatible device being in use or a data-only setup. 800Mhz doesn't work with any devices that rely on 2G/3G for voice calls.

Out of interest, where in the country are you?

[Konvex]

@bristolian 

That's very interesting, thanks 🙂 I'm on the west coast of Scotland, in the middle of a glen.

The strange thing is that one SIM can be affected like this, but another one is unaffected, when both are used in exactly the same location and in the same equipment e.g. a router.

Is there any reason that one would have this issue and another one wouldn't?

[bristolian]

There's extensive use of 800Mhz in the Highlands & Islands, so that can't be ruled out. Equally if in a glen, the 2 sectors could be 180degree apart covering in opposing directions, but the principle is the same.

Are both SIM on PAYM (not PAYG) and is the affected one from a data device?

[Konvex]

@bristolian  Yep, the infill mast is 800Mhz - I remember that from looking into it six months ago.

Both SIMS are PAYM and "normal mobile phone SIMs", but one has been used in a SIM router for 6 months (with no issues) and the other is in my mobile phone for calls. The router one is the one that is playing up now. Currently, I have swapped them and the mobile phone SIM is currently working in the router with no issues.

This morning, I took the bad SIM out in my phone again along the glen for a mile or two, and it connected. I have brought it back and not touched it and it's still connected at the moment in the phone. I did this the other day though and when I put it back in the router, it developed the same problem again.

Is there something I can do to try and diagnose things further?

[Konvex]

@bristolian 

An update…

Now, My mum’s phone has the same issue. What happens is, if she travels along the road, the phone connects and she can call, text, etc. When she comes back home, everything is fine until she switches the phone off and on again. Then, it’s “emergency calls only” until she goes along the road to “sync it up again”.

[bristolian]

Is there a need to switch any individual phone when at the problem location, other than for fault diagnosis?

Does the affected device eventually come back online after a period of time?

[Konvex]

@bristolian 

There is indeed the need to switch phones. Currently, my mobile phone number is in my router, as it is the only way I can get the house connected to the net. This means I don't have my mobile. Also, I am paying the higher price on the other problem number for unlimited net and it's the SIM that's used for the household internet.

The problem SIM does not correct itself over time i.e. once it is not working, it will stay not working until I take it a few miles along the road.

Here is another experiment that I did:

I took the problem SIM a few miles along the road so it connects. I then took it back home and it is still connected. This problem SIM stayed connected and working in my phone for over 24 hours. I then switched it off and on, and immediately it had the issue again.

It's like doesn't want to initially sync up with the mast, but if it's already on when it comes into range of the mast, it's fine.