ATL 5G R16 (RG520F-EU) - Very low upload speed in 5G NSA

RouterOS Beginner Basics
1

Hi everyone,

I'm experiencing a strange issue with my new MikroTik ATL 5G R16 and I'd like to know if anyone has seen something similar.

Hardware

  • Router: MikroTik ATL 5G R16
  • Modem: Quectel RG520F-EU
  • RouterOS: 7.23.2 Stable (also tested 7.24rc1)
  • Modem firmware: RG520FEUEAR03A07M4GX
  • Operator: MEO Portugal

Comparison

The ATL replaced a ZTE MC889A Pro installed in exactly the same location.

Everything is identical:

  • Same SIM card
  • Same operator
  • Same antenna position
  • Same Ethernet cable
  • Same PoE injector
  • Same local network

With the ZTE I consistently obtain:

  • Download: 400–450 Mbps
  • Upload: 45–55 Mbps

With the ATL I consistently obtain:

  • Download: 420–470 Mbps
  • Upload: only 10–13 Mbps

So download performance is excellent, but upload is approximately four times lower.

What I have already tested

  • RouterOS Stable and Testing
  • Modem firmware A06 and A07
  • LTE only
  • 5G NSA
  • Automatic band selection
  • Manual LTE band selection
  • Various LTE band combinations

The behaviour is always similar.

LTE-only

When forcing LTE Band 7 only, upload improves considerably.

Typical result:

  • Download: ~50 Mbps
  • Upload: ~23 Mbps

Signal quality:

  • RSRP: -84 dBm
  • SINR: 12 dB

5G NSA

Using LTE B1+B3+B7 with NR n78:

Typical Speedtest:

  • Download: 420–470 Mbps
  • Upload: 10–13 Mbps

Typical monitor output:



Primary LTE band: B1 or B7 (depends on network selection)

NR band: n78 (90 MHz)

LTE RSRP: around -84 dBm
LTE RSRQ: -11 to -14 dB
LTE SINR: 0–2 dB

NR RSRP: around -70 dBm
NR SINR: 13–17 dB

The LTE Primary Cell changes depending on network conditions (sometimes Band 1, sometimes Band 7), but upload performance remains almost identical.

Carrier Aggregation

AT+QCAINFO reports:



PCC  LTE Band 1 or Band 7
SCC  LTE Band 3
SCC  LTE Band 7
SCC  NR Band 78

depending on the serving cell.

Additional observation

I also noticed something unexpected.

If I enable Use Network APN, the modem registers on the network but no Internet connection is established.

The connection only works if I manually configure:



APN: internet

I'm not sure whether this is expected behaviour or another indication of a compatibility issue.

Questions

Has anyone observed similar upload limitations with the RG520F-EU in NSA mode?

Could this be related to:

  • EN-DC implementation?
  • Uplink Carrier Aggregation?
  • MBIM driver?
  • Quectel modem firmware?
  • RouterOS?

Any suggestions for additional diagnostics or AT commands would be greatly appreciated.

Thank you!

2

Upload goes only via PCC channel…

Then try different cell, compare same cell with same PCC…

3

This is rare and is vissible in Cellular CA bands.

Try enable only B1 and n78 (other disable) and direct the antenna better, This Is only way (better direct the antenna, it's a directional antenna,.: feel free to try to move away from the BTS by 90°, what will it do)

4

Having to specify the APN is very common, that is not the problem, it is (mostly) expected.

Probably you will have to test with different queue types[1] and/or try smaller MTU sizes.

[1] which implies disabling fasttrack

5

ora boas... tenta colocar o mtu do lte1 em 1464 e verifica se melhorou.... e verifica se o queue interface esta em fq_codel... ja deve tar por default mas mesmo assim... não custa verificar

6

@ffernandes obrigado pela sugestão.

Verifiquei a configuração e não tenho qualquer Queue (Simple Queue ou Queue Tree) configurada. Apenas existe a regra FastTrack por defeito do RouterOS.

Vou experimentar reduzir o MTU da interface LTE para 1464 e também testar temporariamente com o FastTrack desativado para verificar se existe alguma alteração no upload.