I believe this ad server which TM employs to push their ads is infected with some sort of trojan or malicious coding.

It'll DDoS the targeted Unifi IPs and disconnect you temporarily by their DPI firewall at their headend for suspiscious activity,

Can anyone trace the source link of their ad server or IP? Maybe can implement hosts blacklisting and block that particular IP in your firewall?

Try to find the source of the ad server linked to pushing this TM related ads and blacklist/block it.

Also try using a VPN to see if this sudden disconnection re-occurs.

TM is known to employ one of the nastiest surveillance equipment in their data centres in the world due to Malaysia's political scene which gets triggered very easily. We've been making news in the world for this to the level that we've even exceeded Singapore in this field.

This is similar to using torrents when you overload too many connections(deluge) until your ISP will temporarily block/disconnect you suspecting of malicious activity.
Somehow this adserver is getting red flagged by their DPI firewall causing their concentrators to disconnect their users.