My side no issue.
Teluk intan.
Where is ur area?

All Telcos need to follow Govts SOP for the free 1gb which for educational purposes only.

Buy 20gb promo if needed high speeds, or RM5/10 addon data for extra 20gb each.

the FUP so far noone knows the exact amount. their website didnt state any number. have to dig a bit to find out.
watching HD or 4K depends on your coverage. if you have good coverage then 6mbps should be 'good enough' to stream movies.
but u can try first with 20gb (Rm20) to see if it is enough.
if it is, then u can keep buying the 20Gb everytime the data depletes.

is your kids using your phone to access the internet or you turn your phone into hotspot/thethering?
If you turn your phone into a hotspot, there's no telco in Malaysia that provides unlimited hotspot data.  Unlimited data is applicable for own device usage only.  If you buy unlimited data from yoodo, you're given 6GB of data for hotspot usage. If you need more than that (hotspot quota), you need to pay extra.

Just a word of advice.
4K video will consume around excess of up to 30Mbits / sec . And this is with Youtube 4K videos.
HD wise, even 6Mbps is sufficient. I've tested this already.
If you are still persistent on 4K, you're better luck with DIGI , or any home fibre plans.

BTW I'm using Umobile and also using Yoodo.
Using those aftermarket modems you mentioned, especially those below RM 200 (which look like clone Huawei modems) , usually can get up to 18Mbps at best and higgly dependant on area. Reason is because they dont support CA .
If you really want better performance, you need to look for Huawei 4G modems, though it will be pricier.

Haha this is where you are mistaken.
Mbps is already Megabits per second. No conversion required. Therefore 18Mbps is 18 Megabits per second.
If really I mentioned is 18 MBps then yes it's equivalent to
151Mbps. MBps is Megabytes per second. Mbps is Megabits per second.

See the difference between the Capital letter B and small letter b.
Usually speed test is quoted in Mbps by default.

Continuing from our earlier discussion this is another screenshot.
Another Yoodo line, but with 3Mbps unlimited.
This time device is using wife Samsung Galaxy Tab S7 FE
Capable of LTE-A since it shows 4G+

See the big difference in device?

Hi zhixie,
The download speed I shared on the 2nd post, is unlimited plan and measured with 4G+ (LTE-A).
Below is today's speedtest in a different area

iphone can use 5g from yoodo? i subscribe but no 5g