Comporium Speed Test

Comporium is not a household name outside of the Carolinas, and that is perfectly fine by them. This family-owned telecommunications company has been serving the communities around Rock Hill, Fort Mill, Lancaster, Chester, and York County in South Carolina — plus parts of North Carolina — since 1895. That is not a typo. They have been at this for well over a century.

What makes Comporium interesting in 2026 is their aggressive fiber buildout under the Zipstream brand. While national giants like AT&T and Xfinity make headlines, Comporium has been quietly running fiber to homes across the Charlotte exurbs — an area experiencing explosive population growth. If you moved to Fort Mill or Indian Land in the last few years, there is a good chance Zipstream is your fastest option.

Figuring Out What You Actually Have

The single most important factor in your speed test results is whether your home is connected via Zipstream Fiber or Comporium Cable. Both can advertise "1 Gigabit" plans, but the underlying technology produces very different outcomes:

If your upload speed roughly matches your download speed, you are on Zipstream. Fiber connections deliver symmetrical bandwidth, so a 1 Gig plan should test around 940/940 Mbps on a wired connection.

If your download is fast but your upload is stuck around 20-50 Mbps, you are on cable. That asymmetry is a dead giveaway. Cable networks use DOCSIS technology that prioritizes download bandwidth at the expense of uploads.

Not sure which one you have? The easiest tell is the equipment in your house. If you have a cylindrical white Calix GigaSpire unit, you are on fiber. If you have a rectangular Arris DG9450 or DG3450, you are on cable.

Your Equipment and How to Access It

Comporium installs different hardware depending on your connection type, and managing each one works differently:

Cable Customers — Arris Gateway

The Arris DG9450 (or older DG3450) is your combined modem and router. You can access its admin panel for changing Wi-Fi settings, checking signal levels, and diagnosing issues:

Inside the admin panel, navigate to the Connection Status page. Look at your downstream signal levels — they should fall between -7 dBmV and +7 dBmV. If they are outside this range, you likely have a signal issue caused by damaged coax cabling, a bad splitter, or a loose connector.

One detail specific to the DG9450: it has a 2.5 Gbps Ethernet port (usually marked with a different color on the back panel). If you are on a plan faster than 1 Gig, you must use this port — the standard 1 Gbps ports will bottleneck your connection.

Zipstream Fiber Customers — Calix GigaSpire

The Calix GigaSpire is a cloud-managed router, which means most configuration happens through the Comporium app or the Plume app rather than a traditional web interface. You can view connected devices, run speed tests, manage parental controls, and change your Wi-Fi password — all from your phone.

If you prefer more advanced control (port forwarding, static routes, VPN passthrough), you may find the app-only approach frustrating. In that case, ask Comporium about connecting your own router directly to the GigaSpire or to the ONT, bypassing the managed equipment.

Issues That Are Worth Troubleshooting Yourself

Before calling Comporium support, a few common problems are easily fixable at home:

Plume pod showing slow speeds: If you have satellite Plume HomePass pods for mesh Wi-Fi coverage, remember that each "hop" from the main router to a pod reduces available bandwidth. Testing through a pod in a back bedroom will always be slower than testing near the main unit. If a specific pod seems especially weak, unplug it for 30 seconds to reset its wireless backhaul connection.

Blinking US/DS lights on Arris (cable): The Upstream/Downstream indicator lights should be solid green when your modem is locked onto Comporium's signal. If they are blinking, the modem is searching for frequencies. Check that your coaxial cable is screwed in tightly at both the wall plate and the modem. Also inspect the cable for any visible kinks, cuts, or crushed sections.

Fiber outage after yard work: This is surprisingly common in the Rock Hill and Fort Mill area. Comporium's fiber drop cables are buried relatively shallow in many neighborhoods. Landscaping crews, fence installers, and even aggressive raking near the property line can nick or sever the fiber. If your Zipstream goes completely dead after someone was digging nearby, report it immediately — Comporium will need to dispatch a crew to repair or re-run the drop.

When You Genuinely Need Comporium's Help

Some situations require a technician or network-side fix. Contact Comporium at 888-403-2667 if:

• Your Calix GigaSpire shows a solid red optical light. This means the fiber strand is physically broken or the ONT has failed.
• You are on Zipstream Fiber but your upload speed is stuck below 100 Mbps. This can indicate a provisioning error on your account — the system may not have your plan correctly configured.
• Your Arris modem's globe icon blinks continuously. This means the modem has a physical connection but cannot get an IP address from Comporium's DHCP server — a server-side issue.
• You need to set up bridge mode on your Arris gateway to use your own router. Comporium support can walk you through this or configure it remotely.

Comporium's Advantages (and Limitations)

There are real advantages to being a Comporium subscriber that are easy to overlook:

• No data caps on any plan — cable or fiber. In an era where Xfinity caps at 1.2 TB and AT&T caps non-fiber plans, this is significant.
• Local customer support. When you call Comporium, you are talking to someone in Rock Hill. Technicians live in the same communities they serve. That means faster response times and people who actually know the neighborhoods.
• Multi-gig fiber availability in many Zipstream areas. 2 Gbps and 5 Gbps residential plans are available in select neighborhoods.

The main limitation is obvious: geographic coverage. Comporium only serves a relatively small footprint across the Carolinas. If you move outside their service area, these speeds go with you. Additionally, their cable infrastructure in older neighborhoods can show its age during peak evening hours.

Comparing Comporium to Local Alternatives

In the Charlotte metro area, several providers compete for the same households:

• Spectrum is the primary cable competitor across much of Comporium's footprint. Spectrum offers up to 1 Gbps cable with a no-contract model, but lacks symmetrical upload speeds.
• AT&T Fiber is available in parts of the Charlotte region and offers symmetrical multi-gig speeds similar to Zipstream. AT&T's pricing tends to be competitive but may include equipment fees.
• Google Fiber has reached parts of Charlotte proper. If you are close enough to the city, Google Fiber's pricing and performance are extremely competitive — but their footprint does not extend to Comporium's more suburban and rural coverage areas.

Answers to Questions We Hear Often

Can I get Zipstream if I currently have Comporium cable?

It depends on whether Comporium has run fiber to your specific street. Call 888-403-2667 or check the Comporium website with your address. In many neighborhoods around Rock Hill and Fort Mill, fiber is now available alongside existing cable. The upgrade requires a technician visit to install the new equipment — there is no self-install option for fiber.

Is Comporium good for working from home?

On Zipstream Fiber, absolutely. Symmetrical speeds mean video conferences, VPN connections, and cloud file syncing all work smoothly. On cable, video calls still work well for most households, but if multiple family members are on simultaneous video meetings, the limited upload bandwidth (20-50 Mbps) can become a bottleneck.

What is the contract situation?

Comporium offers both contract and no-contract options. Contract plans typically come with a lower monthly rate, while no-contract plans offer flexibility. Ask about both when signing up to see which fits your situation.

Can I use my own modem on Comporium cable?

Comporium generally requires the use of their provided equipment for cable service. For Zipstream Fiber, you can often connect your own router behind the Calix ONT. Contact support to discuss your options.