ZTE MF286d low DL performance

I have OpenWrt 22.03.2 installed on my MF286d and using uqmi.

I never get over 150Mbps even though I have 2 * 20MHz CA in downlink.
The UL is OK, 66 Mbps.

I´m testing with Spedtest on a PC, connected with ethernet cabel to one LAN port.

What can I do to improve the DL speed?

Revision: BD_TELIAMF286DV1.0.0B12
SVN: 12
IMEI: 8667540xxxxxxx

+ZNLOCKBAND: 20080800c5,2000000680380

+ZCAINFO: 338, 3, 11098, 1750, 20.0; 338, 2, 7, 3350, 20.0;

+ZRSSI: -59,-8,-31,30.0

The base station support:

Band	Freq	BW
1   	2100	10
3   	1800	20 + 10
7   	2600	20 + 20
8   	 900 	10
20   	 800 	10
28  	 700 	10

Have you rouled out other bottlenecks?
Like ISP cap, BTS congestion?

My subscription in unlimited and the base station is unloaded. I get over 600Mbps with my Samsung S21, without 5G.

I don´t know if the Telia branded firmware has any limitation when using it with a non Telia SIMcard.

Is it possible to upgrade the firmware to a generic one?

Never updated the modem but it's possible to do it, see here for explanation (post n.2422):

ZTE MF286D - Openwrt (Page 97) – Hardware – eko.one.pl

The real problem is: you are on Nordic B12 firmware, which is already the last one issued.

OK, I have the latest FW.

But, is there no one who has got a higher DL throughput than 150 Mbps?

Here in Italy Is almost impossibile to achieve that Speed with a cat12 device.
B3 is almost always congested as B20.
B7 has reduced coverage.
B1 has reduced bandwidth until 3g will be fully retired.
So I can't help...
Have you tried to see on YouTube? I saw there are a lot of 286d reviews with speedtest mentioned.