1. Connect a laptop or desktop directly to the router using an Ethernet cable to make sure you are definitely getting 300Mb/s. If yes, then proceed with the next 2 steps
2. When using above 50Mb/s, always use 5GHz, never 2.4GHz
3. Set your 5GHz bandwidth to 80MHz. Not 20, not 40, not auto, not 20/40/80. Not sure if the DIR-842 allows you to set it to 80MHz only or not. If not, then time to dump it and get a better router such as the ASUS RT-AX56U

This is where you can find it, don't ask me how to access your router configuration, I don't have time to spoon-feed you with every detail. Google it yourself

Do we actually need to upgrade TM stock router firmware? I didn't upgrade mine since Unifi installed it, any benefits of upgrading? Thanks

Can TM router flash international firmware?

My D-Link DIR-842 still v3.01TM, firmwre verison dated May 2018

can , but your USB wont work (mostly , i dun need usb)
the benefits is you can get security patch , or greater encryption like WPA3

I didn't do any setting on it, by default should be auto update isn't it

I noob on this, any benefits for updating?

When i check for new firmware update

Or you can ask TM technician to upgrade your router firmware via remotely.
Since every router supplied by the TM has a TR-069

Anyone from Penang experiencing slow connection at the moment?

Try Speedtest and result show 8mbps only.

Anybody experience extreme lag recently on 1.9.1.9 Dns? it used to be quite zappy until recently, I was so frustrated thought its network issue, changed thr dns and things are zappy again.