GL-X3000 Spitz AX with Tmobile 5G, speed test is ok but not linux ISO file

I use GL-X3000 Spitz AX with Tmobile 5G. It is working after I modify IMEI and it is great for a week.
However, I have an issue about big file downloading.
Speed test is still ok (300Mbps for 1 min test time), but not for Linux ISO file (or single huge file).
It shows fullspeed (300Mbps) for 2 sec, then back to 0Mbps. So now I switch back to Tmobile home gateway and everything is ok including big file.

I am wondering if someone can help.

My test is OK. Have you opened other services?

Is there a limit to your sim card plan?

Hi lizh:
After I upgrade latest firmware “release50303”, the issue is fixed.
Not sure what the reason is. But thanks anyway.