5G Upload speed recently died

[originalcopycat]

In the last two weeks I've gone from speeds of 500+ Mbps down/70+Mbps Up to now 40Mbps down / 5Mbps Up.    Occasionally my download speed is around 300Mbps, but my upload speed never goes above 7Mbps.  This is a real problem for me as we work from home and need to sync files and video call.  I cannot live with upload speeds that slow and they are a 90% reduction of what I had when I bought the service, 9 month ago.

I've had a call open with Network Team for over two weeks and they have no solution.   I'm on the Zyxel NR5103E on firmware b14.   I have "Excelllent" 5G signal (-89 RSRP).   I have factory reset multiple times. Performance identical whether on WiFi or Ethernet.

Nothing else has changed.

Three called me yesterday to say there was a network fault but they had fixed it.   The issue persists for me, though.  Three are unable to fix the issue and are unwilling to release me from contract.   What should I do?  I will have to buy a service elsewhere but I shouldn't have to pay for a service that is severely degraded and basically unusable for me.

[sc1999]

I don't have 3 broadband but I  have always complained about my 4g upload speed.  Vodafone is 10mb down 10mb up, 3 is 25mb down 0.25 up. Yes 0.25 up which won't allow a webpage to open. I would love to know why 3's upload is always pathetically slow.

[originalcopycat]

To this, now.From this when I purchased.

[Anvil_Iron]

Which cellular bands is the Zyxel router connected to?

[originalcopycat]

Edit: Redacted data in original image.

[Anvil_Iron]

5G seems fine but 4G is poor which will affect both UL and DL speeds. The app is misleading when is says "Excellent" signal strength as it doesn't take 4G conditions into consideration. 

What is the location of the router? It may need to change to an area closest the mast and higher.

Manually changing cellular bands may help to at least give a better UL speed. Try adding B32 and restart router. If not, remove B1 & B3 and replace with B20 & B32 with n78.

This maybe a temporary problem with the network/mast so try B1 & B3 again at some stage.

[originalcopycat]

Thanks, I will try.

I received a replacement device today and, bizzarely, have a completely different result.  This "new" device (was not entirely clean, so assume it's a refurb) will not connect at all to 5G.    It's on B12 firmware (not B14 like my other one), but it will connect to 4G+ and when it does I get 20Mbps+ upload (much, much faster than my one that connects to 5G!??!).     Really odd, no?