credit card terminal not getting an ip address

I'm going to throw out the facts that I have in case any of this ties it together for anyone...

• ethernet connection to credit card terminal just started failing (set for dhcp, not getting an ip address)
• tried 2 different cables, plugged into 2 different ethernet ports
• brought it home, used one of the same cable... plugged into my own home cable modem (on Comcast) and it worked fine

This could be related to ongoing problems that I've been having with our business class service. Upgraded to faster service in December. They put in a new docsis 3.1 gateway and now have "securityedge" and the cradlepoint connection pro... honestly I don't want/need either of those... just wanted faster internet speeds for our customers.

New service was blocking all sorts of websites, set security to minimum and it still blocked sites that we weren't expecting (like a college student that wanted to turn in a paper through a college online portal).

• nest thermostats (3) going on and offline all the time since new hardware
• "static ip" changed recently and had to call to have it reset
• a week ago Saturday had to call a tech when I tried to do port forwarding and couldn't access the screen to do it (click on "add service", get asked for my gateway login info, repeat over and over again... tried to 2 browsers). Tech had firmware rolled back and his support number told him to replace the gateway.
• last Tuesday got a new gateway, crashed on Wednesday night and internet was showing offline at the router. Comcast support said they couldn't ping the router, said they'd get refer me to level 2 and I'd hear back in 24-48 hours.
• Called Thursday morning (didn't want to wait 1-2 days) and the tech on the phone tried 3x to get me back up and then succeeded. Scheduled a truck roll for later that day, but my tech from the other day saw it and said that a new router wouldn't fix it.
• Internet has been up since last Thursday but I suspect the credit card terminal hasn't been up since then (we only use it on weekends)

Anyone able to connect these dots?  I'm inclined to get my own modem but they said I can't with a static ip (which I would abandon to get more stable all around internet).

I've tried opening all ports on the comcast router too... credit card terminal still not working...

Sorry for the info dump above.