@gazza35 

** UPDATE **

I've been playing around with the settings and changed it to 4G Only and all of a sudden it picked up the network and started working fine (albeit with a very weak signal) 

Then changed back to 5G Preferred and straight away it failed again, so it looks like the issue is to do with 5G and possibly signal strength.

Strange as when I was trying it in the office earlier there's a good signal strength there as I'm on the same provider with my phone and I had a full and strong 5G signal on the premises

  @gazza35 

Hi

It looks like only the 5G connection is having issues, so we would like to gather some information to analyze further:
1. You mentioned that 5G can be used normally when the SIM card is inserted into the mobile phone. Were the mobile phone and Deco tested in the same place?
2. Please change the settings to 5G preferred and then take a screenshot of the internet page and share it with us (we may need to check the internet page information when there is no network).

  @Joseph-TP 

Hi Joseph

Many thanks for the response

Yes, it does seem to be just the 5G that is causing issues.  I can get it working pretty much every time with 4G now but absolutely nothing at all on 5G.

To answer your questions:

1.  I didn't try this specific SIM card in a mobile phone but in another older TP-Link router (4G only) which explains why it was working fine now that we know the problem is 5G related.  I do have an EE 5G SIM in my mobile phone and can confirm that is working fine with a good 5G signal from the exact same location where I tried 5G with the Deco originally.

2.  I have taken screenshots from both 4G Only and 5G Preferred so you can see the difference.  Please note that this is not from the original location that I first tried the Deco, I have brought it home to test further and the signal strength is pretty poor here for some reason.  The end result is exactly the same though, working fine on 4G but as soon as I switch to 5G I get the red light and it's reporting no signal.

4G Only:

5G Preferred:

Many thanks

  @Joseph-TP 

Hi Joseph,

An update from further testing this morning.

I've brought the router into my other office location which is in the city centre and there's a much stronger signal here.  Started in 4G again and all was well.  Decided to do a speedtest with Ookla and got a very respectable 140mbps down which was impressive.

I then switched to 5G Preferred and exactly the same happened again, ie loss of signal and the red light.  I powered the Deco off and back on and it came back to a red light.  I got distracted by something else so left it like that for a while.  When I came back the light was solid white which I'd not seen before.  When I looked at the manual that said it was a 5G signal!  So much to my surprise I went into the app and yes, it's reporting as 5G with good signal strength so was very happy with that. However when I've done a speedtest again with Ookla on 5G I'm only getting between 8mpbs and 11mpbs down versus 140mbps on 4G so something still not right unfortunately.

I'll send screenshots now with the 5G connected:

  @Joseph-TP 

Further update, I've just changed server on the Ookla speedtest and am getting 288mbps down now so much better.

Could the issue simply be signal strength?  Stil intrigued why it locks up in other locations with the red light though.  Will try again later in the other suburban office where this is going to be the main source of internet.  

** Even further update! **

I've just retested the server I got 288mpbs with and I'm only getting around 15mpbs now.

The original and more local server I initially tested and only got 11mpbs with, I'm now getting 438mpbs!  

Seems to be a wild swing in download speeds, not sure why that would be.

  @gazza35 

Hi

Thank you for the details.

Based on your testing (different places), it looks like the 5G light turning red has a lot to do with the environment. When you move Deco to an area with stronger 5G signal, Deco 5G works normally.
When switching speed test servers, you may encounter varying speed results due to different geographical locations, network connections, and loads. As long as there is a speed test server that can achieve the desired speed, you don't have to worry too much about Deco's speed.

Good day.

  @gazza35 Hey there, im having the exact same issue with the same router and EE sim. Could you please show a screnshot of what your APN is? with the EE card on the router so i could test it on mine and thanks. And any news about your speeds now?