There are several important aspects to understand about routing internet traffic through cellular networks, especially compared to fixed-line broadband connections.

Underlying Technology and Infrastructure:

Radio Waves: Cellular networks rely on radio waves to transmit data between your device and cell towers. This is a shared medium, and signal strength and quality can be affected by distance from the tower, obstacles (buildings, terrain), and interference.
Mobile Network Operators (MNOs): Your connection is managed by a mobile network operator (e.g., Verizon, AT&T, T-Mobile in the US). They own and operate the cell towers and the core network infrastructure.
Spectrum Allocation: MNOs operate within specific radio frequency bands (spectrum) licensed by government authorities. The amount of spectrum available and the technologies used (e.g., LTE, 5G) significantly impact network capacity and speed.

IP Addressing and NAT (Network Address Translation):

Dynamic IP Addresses: Typically, when your device connects to a cellular network, it's assigned a dynamic IP address. This means the IP address can change each time you connect.
Carrier-Grade NAT (CGNAT): Due to the limited number of public IPv4 addresses, cellular carriers often use a technique called Carrier-Grade NAT (CGNAT). This means multiple subscribers share a single public IP address.

Implications of CGNAT:

Inbound Connections: CGNAT can make it difficult to host servers or directly accept incoming connections to your device from the public internet. This can affect things like remote desktop access, running game servers, or accessing security cameras from outside your network without specific workarounds (like port forwarding if supported, or using third-party services).
Port Conflicts: In rare cases, multiple users behind the same CGNAT IP address might try to use the same destination port, potentially causing issues.
Troubleshooting: CGNAT can sometimes complicate network troubleshooting.

Performance Characteristics:

Latency (Ping): Cellular network latency can be higher and more variable than fixed-line broadband due to the wireless transmission and the complexity of the mobile network infrastructure. This can affect real-time applications like online gaming and video conferencing.
Bandwidth (Speed): Download and upload speeds on cellular networks have improved significantly with technologies like LTE and 5G. However, speeds can fluctuate based on network congestion, signal strength, and your specific data plan.
Jitter: Variations in packet delay (jitter) can also be more noticeable on cellular networks, potentially impacting the quality of voice and video calls.
Data Caps and Throttling: Most cellular data plans come with data caps. Exceeding these limits can result in significantly reduced speeds (throttling) or overage charges.

Security Considerations:

Encryption: Cellular networks use encryption protocols to protect data transmitted over the air. Modern standards like LTE and 5G offer strong encryption.
Public Wi-Fi Risk (Tethering): If you use your cellular connection to create a Wi-Fi hotspot (tethering), be mindful of the security of that Wi-Fi network, especially if it's publicly accessible. Use a strong password.
Mobile Malware: Devices connected to cellular networks are still susceptible to malware and other security threats. Ensure your devices have appropriate security software.

Mobility and Coverage:

Primary Advantage: The key advantage of cellular internet is its mobility. You can access the internet from virtually anywhere within the network coverage area.
Coverage Limitations: Coverage can vary significantly depending on your location and the MNO's infrastructure. Rural areas might have weaker or no coverage. Building penetration can also affect signal strength.

Cost and Data Plans:

Generally More Expensive per GB: Cellular data plans tend to be more expensive per gigabyte compared to fixed-line broadband.
Variety of Plans: MNOs offer a wide range of data plans with varying data allowances, speeds, and features. Choose a plan that suits your usage needs.

Roaming:

If you travel outside your MNO's primary coverage area, you might roam onto another network. This can incur additional charges or have different data speed limitations.

In summary, routing internet traffic through cellular networks offers unparalleled mobility but comes with trade-offs compared to fixed-line connections. These include potential limitations with inbound connections due to CGNAT, variable performance based on network conditions, data caps, and generally higher costs per gigabyte. Understanding these aspects is crucial for making informed decisions about using cellular networks for internet access.