Issues With Router Admin Login

I am an Xfinity prepaid customer with the default router that came with the plan (and have been for several years now).  I have been having some issues recently with strange processes found running on my operating system and my paid VPN randomly being rendered unable to launch (strangely enough even after I uninstall/reinstall). 

This prompted me to login to my router admin page at 10.0.0.1 a few days ago to change my password and review the settings/logs.  Immediately when I visited the login page I received a warning that there was an "Insecure Site, Hackers Could Steal Your Information" warning.  I tried 3 different devices, with different browser, cleared cookies and received the same warning each time.  I clicked on "More Info" and it sited a certificate issue tied to the domain myrouter.io.  I also received the same error when trying to visit via HTTPS.

Because I had no other choice and had my password set as the default, I bypassed the warning and logged in anyway.  I changed my password and reviewed my logs to see that on a daily basis that there were unknown "Add/Delete Port Mapping" entries that had been found in the logs on a daily basis going back for several weeks for ports 3074 and 50637.  I am not to well versed as to what triggered these but I am certain that I had not logged into my router admin page for the entire duration of when these log entries were showing to have taken place.

Today I wanted to go back into my router admin page to review the logs again and see if anything new or suspicious showing and this time when I tried to visit 10.0.0.1 the page stalled and I received "The connection has timed out" errors every single time that I have tried to log back in over the course of the last 12 hours.  I tried once again with multiple devices, multiple browsers, ensured the firewall was not active, plugged my laptop directly using an ethernet into my Xfinity Modem, cleared cookies in all devices, reset/unplugged my router numerous times, I tried reaching the page with the same result @ 192.168.100.1, reviewed browser settings and I am still receiving the same error.

Any ideas or further measures that can be taken so that I can finally get back into my router admin page?