For those that may share my frustration with tunnel speeds on Charter Spectrum connections.
I have Charter Spectrum Coax connections, Comcast Coax Internet and Comcast Enterprise Fiber, Verizon & Sprint LTE Modems and a couple fiber connections at my colo.
When running either EoIP, IPIP, GRE or IPSEC the throughput is just horrible when I used any of my seven Charter Spectrum connections. I would see 18-30Mbps. From the other providers tunnels work at either full bandwidth capacity or until router CPU maxes out.
After a couple days escalating up the chain in search of a higher intelligence I made it to the business concierge team and they took a detailed report and had one of their N.O.C. technicians reach out to me. They claimed over and over that they are not shaping the traffic and the only thing that may cause this would be the modem. And of course with their business Internet you cannot supply your own modem. The tech suggested scheduling a service call and replacing my current modems with one of their Hitron brand modems to see if that rectified the issues. Surprisingly they had a tech out the very next with a Hitron modem and now I have no speed issues whatsoever. I have their 300Mbps plan at one location and I can speedtest across a EOIP,IPIP,GRE tunnel at 300Mbps no problem.
If you happen to have this same experience ask for a Hitron modem as their other units massively restrict encapsulated traffic.