Connection keeps dropping numerous times a day + slow internet.

I have been experiencing random connection drops for past month or so. Everything was working fine earlier (with same wiring and same equipments - Arris SB8200 modem + Asus RT-AC87U).
Upon checking my modem log, I see countless MDD message timeout and SYNC Timing Synchronization failures.
FYI, I do not have any splitter in use. My modem is connected directly to the outlet.

I have gone thru various google search results and other threads on this forum. Almost all of them concluded to be connection issues.

Could someone please take a look and give me some advice please?

Also, I wanted to know if always connection/wiring is the culprit in cases like this? Or could this be a modem issue as well??

I called xfinity customer care, they said they could send out a tech to take a look, but if this turns out NOT to be a connection issue on their end, they'll charge me $70! 😞

Event log screenshots are shared here: https://postimg.cc/gallery/dqtJ2sV

Many thanks in advance for you help.