I'm probably going to make this my final post regarding Three 4G. This is just a final say, you could say. I just want to just add to my initial "experience".
First of all, today I realised that the B525-23a
does work with Three's LTE CA implementation. I felt rather stupid because I bought the 65a because of that.
I couldn't get it working before, perhaps due to poor positioning or because I had forgotten I had initially specified a band in the settings as opposed to setting it 4G auto. I should say I have not extensively tried to understand which bands are being used, but I presume it does indeed use inter-band B3+B20 (at least locally) - I really don't know, but may try some stuff in the future.
I have been using the 4G connection as a secondary connection for the past few months and my experience has been relatively consistent, but I have noticed that during the day the speeds have been a bit more all over the place as opposed to the times I typically use my connection (evening and night). During the height of the day up until some time in the evening, speeds are as low as 20-25 Mbps, usually averaging 30-40 Mbps, with peak being not much higher. At these times of the day, having an external antenna and good positioning makes very little difference.
I still haven't watched live streams (such as live TV) over the network because I really have no interest. But what I have tried recently is streaming games from my VDSL2 connection over the internet to my 4G connection using Steam Link (I used it on Android). From the limited testing, using the smartphone on 5 GHz Wi-Fi in the same room, I found it to be absolutely unplayable some to most of the time - at least during the day, regardless of bandwidth setting. Night time was a lot better, but there were still problems - the application doesn't say there is any frame loss in the network test, but the latency can spike sometimes. I haven't tried Ethernet, but given the improvement at night compared to during the day, I would be very confident that switching to Ethernet would make so very little difference. Perhaps it needs some tweaking, but I think it is almost as good as it will get.
So this update doesn't really change my view on using Three for broadband. I think it's still a great deal if you are getting it for £20/m or under as long as you are aware of the caveats. In general, expect web browsing to be good, downloads to be somewhat fast, but live streaming and game streaming services may be impacted by latency and varying bandwidth.