No way to get 300mbps,unless u tarik the entire wiring to yr house

Your friend's Unifi account is 300mbps while yours unifi account is 100mbps. Am I correct?

If you say modem, then that is white color ONT modem.. (Normally supply by Huawei)
Am I right?

You will need his modem, as well as his PPPoE username and password. Theoretically, it might work.

For white color ONT modem, I think you can try as first since whether yours can support or not.
For my experienced, last time I bring my router (without this ONT modem).. No matter my friend is 100mbps.. But my address still only achieve with 10mbps only even use my friend username and password... So predict nid together with ONT modem. (Previously my one is 10mbps while my friend is 100mbps)

BUT another scenario based on TM technical say lah~ (I'm not so sure coz haven't try before).. They say if you bring your friez ONT modem and router to your places.. Your ONT modem might not run properly. Reason is the ONT modem inside setting has set the TM pole (I guess it's white box one) something like mac address or serial number to determine your ID and password. That was the 2 years ago lah..

But of course if there is any issued of internet connections (maybe not stable) during secretly using your friez device,  u don't pandai pandai call cs and request to reset port ya...
(Else, TM cs will feel suspicious about yours.. hahaha..) Because they can see everything your current device router and ONT modem using...

Yes, it'll work provided his house is in the same area as you. You'll also need his Unifi password. Even easier since you can borrow both both modem and router. Just plug and play.

The modem has a password to connect to the local PPPoE concentrator (OLT). The OLT in a different part of town will probably have a different password.

I've tried this with my next door neighbours's modem. Confirm it works. This was when I was waiting for my Turbo upgrade and she got her 500Mbps way earlier than I.

I also tried my mum's modem in my house. Didn't work. She's in PJ and I'm in Kajang.

Also note that the phone number follows the modem so don't or do make as many international calls as you like.