well, prepaid unlimited plans are for phone usage only. umobile probably blocks unlimited plan usage if it detects that modem is used instead of phone.

U Mobile block prepaid sim card plan use with modem
U mobile sim card so advance one
With phone all good, put inside a few modem just show no sim card, or invalid sim card
The solutions is hotspot tethering with phone + RM5 unlimited hotspot

tried umobile prepaid, yes prepaid, digi prepaid n maxis prepaid. all speed is the same. nearest active 5g tower is about 800 meters from my house, but in between my house to that tower there's a huge aeon mall. so my speed significantly reduced. can only get around 300 - 350 mbps only on 5g.

hyperbolic v9 antenna could easily at least double this speed, but very costly, rm300 - 400 with all the cabling included, maybe for future upgrade. for now I'll keep using yes as my main sim bec the cheapest rm25/month for unlimited speed + unlimited 5g data. no point using other telco as 5g speed is about the same everywhere.

attached is my signal (quite bad even though already place at the window. haha) & the speed I able to get around 300mbps. anyway just terminate my 800mbps maxis fibre contract this evening (rm232 monthly, with 6% tax). huge saving for me in the coming months. from rm232 to just rm25 monthly. hehe.