DoS Attacks - from varying sources and ports.

Firmware is 2.5.1.8, says it's up to date.

Modem is a NG CM 1000.

as for the IPs they are all varying and I'm not positive how to determine if they're from an external address - of the 256 lines I pulled from the log, 125 of them are DoS related. An actual attack doesn't make sense to me, but if not this, what would be causing my newly minted spikes and disconnects while gaming?

I have been collecting the logs from two Orbi's (one for over a year, one for 8 months).  These logs record these "DoS Attacks" every day, and this is entirely normal.  Orbi contains a firewall for a purpose. It rejects attempts to connect and has an option to record "interesting things" in the Orbi log.  People have posted comments indicating that Orbi is to "liberal" at classifying random connection attempts as "attacks".

The user can "Disable Port Scan and DoS Protection" on the Orbi web interface, Setup, WAN Setup page.  I believe this will stop the system from spending processing time recording and classifying things and writing them to the log.  I am not confident that there will be a noticable improvement in performance.

Orbi's have a "public IP address", just as we have "public" street addresses and phone numbers. It is almost trivial to create a program which will "scan" IP addresses looking for systems that respond.  This has been happening since the internet was created.  It's like RoboCalls that just dial every possible phone number hoping that some of them will answer.  I can set my phone to ignore certain calls and not ring, but that doesn't make the calls go away.

Since the service problems are serious, I would certainly try checking that box first.