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UMobile's LTE Band 3 = 1800MHz = is still easily blocked by walls. Celcom also uses Band 3 and Band 7.

Unifi Mobile also uses Band 5 = 850MHz (besides using Band 38 and 40) and Maxis also uses LTE Band 8 = 900MHz (besides using Band 7), which are not easily blocked by walls.

Network congestion can happen since each 4G cell tower can only serve up to 60 users at the same time = slow download speed and/or unable to connect.
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In city-high density areas, the mobile telcos erect more 4G cell towers, ie the cell towers are closer together, eg 1 km apart.

In rural-low density areas, they can place the cell towers at maximum 10 km apart.
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No, is limited

Umobile faq

You may set it as metered connection so Windows won't download windows update when connect to your hotspot

Just try to update or download anything 1st before you went hometown

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Yes, it is "illegal" or against the T&C to use U Mobile's phone plans with 4G LTE modem-routers, even though it is technically possible to do so.

U Mobile can detect such "illegal" usage, especially data-hogs, eg use >150GB of Internet data per month = once detected, punitive actions follow.

Other celcos allow or legalize such usage, eg prepaid TM UF Bebas  and postpaid Digi 150 Infinite plans.
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Maybe temporary suspension of line for 1 to 2 days, to serve as an unwritten warning to the subscriber about the "illegal" use of the 4G phone plan with 4G modem-routers or the PdaNet+ app. If subscriber still continues with the "illegal" use after the line has been reconnected, the account may then be permanently  terminated by U Mobile and the subscriber blacklisted from subscribing to U Mobile.

For postpaid accounts, U Mobile may issue an "exorbitant" last month bill to the "illegal" user for non-approved use of "excessive" Internet data for the previous months, eg 1GB = RM1. If the subscriber does not pay the bill, celco-wide blacklist and/or CTOS action may follow.
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