Signal dropping on Zytel and ZTE routers

[igs]

This is a long one, so buckle in ...

I joined Three just over a month ago and got my Zytel NR5103E 5G router. Testing it on speedtest.net, the speed was in the range 70-150mbps which I was happy enough with. However, within the week, I noticed that my signal was under 3mbps, so I phoned 500 and got through to a very helpful chap in level 1 Customer Support. After 45 minutes talking about windowsills, etc., he suggested that I reset the router and that worked, the signal going straight up to around 70 mbps. Success, but over the following weekend I noticed that my signal was crashing down to under 5mbps regularly, five times over two days, but this time I knew that a router reset would fix the problem. On the Monday, I used Live Chat Assistant to get through to a Level 2 Support chap. He checked some settings and asked me to reset the hub. He suggested that the problem was mast congestion, which it wasn't. He changed some more settings and assured me that the problem was resolved. It wasn't, I had the same problems later that night. On the Tuesday, I got through to another Level 2 support chap who eventually suggested that the problem might be my router sim. I followed his instructions and tested that sim in my mobile phone and it worked fine. Meanwhile, I'd lost connection with the chap who had closed the Live Chat Assistant, so I phoned 500 and got through to a very helpful customer support lady who arranged for a replacement router to be sent out and exchanged with my old one, eliminating that as a possible cause of my woes.
The new router arrived extremely quickly and the old one went back, so I was online again within 48 hours. Unfortunately, the line speed issue persisted. I spent several hours searching the world wide web for solutions and eventually came across these pages including https://community.three.co.uk/t5/Broadband/Three-Home-Broadband-Zyxel-NR5103E-drops-connection-and-W... - a post from an extremely frustrated lady whose router signal regularly fails, requiring the router to be reset. Clearly, I'm not the first person to have this problem and reading through the 8 pages of that thread, it seems that many people have faced the same issue with the NR5103E. Following suggestions in that thread, I used the WebUI to access 'Cellular Band'. On Cellular Band, there is something called 'Access Technology' which has four options, NR5G-SA/NR5G-NSA/4G (Auto Switch), NR5G-SA, NR5G-NSA/4G (Auto Switch) and 4G. The first of these was the default, so I experimented with the other three choices, starting with 4G and on that setting, my line speed was fine. NR5G-NSA/4G (Auto Switch) also fine, the speeds matching those I'd had on 4G. At this point, I realised that switching between bands was effectively a soft reset which did the same job as the reset button on the router. Switching to NR5G-SA I got no signal whatsoever - my ethernet and WiFi connected devices were all connected but with no internet. A fifth NR5G-NSA option would have been useful, but it wasn't available to test. After investigating the difference between NSA (Non-Standalone Architecture) and SA (Standalone Architecture), I concluded that from my perspective it doesn't matter. It's quite possible that my local access to 5G is through NSA architecture, so the NR5G-SA option won't work until a brand new mast is built nearby. Nevertheless, my experiments were extremely informative in that it is clear that I get a decent signal. So why did my signal regularly drop from 70mbps to 3mbps and stay there until the router is reset? I concluded that that the problem is that when the NR5103E router auto switches from 4G to 5G, it doesn't auto switch back. So, it appeared that the issue was not my positioning of the hub, my local mast congestion, my sim card or even the specific router I'm using, but rather the entire stock of NR51003E routers which Three are sending out to their customers. I got through to Level 2 Support and explained all of this to the chap there who insisted that there is no problem with the NR5103E routers and my problem was due to work on my local mast which would be completed that evening. I assured him that my problem would not be solved the following day, but he simply continued to insist that the router was fine and that mine was a mast maintenance issue. Of course I was right and once again I'd been fobbed off by Level 2 Support, so the following day I contacted a very helpful lady in Level 1 Support who cancelled my contract and arranged for a bag to be sent to me so that I could return my Zytel router.
At this point, I visited my local Three shop. Having explained my experience over the previous week, the helpful chap there informed me that the NR5103E is rubbish and they have had lots of them returned because they constantly lose signal. Try telling that to Level 2 Support, I thought! He showed me the ZTE MC888 router and I decided to give it a try on a new contract. I got it home and set it up, but guess what! Exactly the same issue. The web interface for this router is quite different to the Zytel model, but I was quickly able to figure out how to do a soft reset by turning the signal off and on, going into Settings then choosing Network and switching between '5G&4G (preferred)' and '4G only', returning to Connection Settings and turning the signal back on again. If nothing else, that's massively more convenient than having to physically reset the router with a phone pin. The problem remains, however, that I'm a couple of weeks into my new contract and I'm still getting intermittent signal drops on my connection.
So where does that leave me other than looking at cancellation again? I'd convinced myself that the problem was with my original NR5103E router, so I got a replacement. When the problems continued, I concluded that it was the Zytel model which was the problem and that view was confirmed by the chap at the Three shop. Now I've discovered that the issue remains with a completely different router model (though I must admit that my new ZTE router's top speed is better than the Zytel's). So what's going on Three? There are lots of your customers here reporting the same signal drop issues, but I don't see any solutions.

[dabbied]

I am experiencing exactly the same issues as you've described with my Zyxel NR5103E. Singal randomly dropping, issues with the router constantly switching to 4G despite great 5G singal around, speeds stuck below 40Mbps. I think I've tried every single possible place in the house to try and position the router to stabilise the signal (including dangling it off the ceiling and using an extension cord to power it...). I have a 5G-enabled phone (also with Three) and the internet speeds are amazing! (300+ Mbps on 5G, tested in exactly the same spot as the router). Issues with the Router dropping connection altogether started after the new firmware was auto-upgraded to: V1.00(ACBJ.0)b14. Issues with slow speeds despite great 5G signal have been there even before that.
I've tried speaking with Three customer service but they're adamant it is a mast problem and nothing to do with the Router. I'm at a loss with it now. Can someone help us?
@JonathanB ?

[igs]

Can Three please tell their Level 2 Support to stop lying to their customers?