Nebra Indoor Miner RPC Unavailable – SOLVED

A number of people are reporting this problem with Nebra Rock Pi miners where it states Miner RPC Unavailable. RPC stands for Remote Procedure Call.  RPC allows a user to perform actions on a machine while being on another machine. It can also apply to the same machine but in a different process.

According to Wikipedia:

“In distributed computing, a remote procedure call (RPC) is when a computer program causes a procedure (subroutine) to execute in a different address space (commonly on another computer on a shared network), which is written as if it were a normal (local) procedure call, without the programmer explicitly writing the details for the remote interaction.”

This appears to be an error in the code and we expect someone at Nebra will sort this issue out soon. It is an issue that affects many users.

For the time being until they do, there are two solutions to the problem:

  • Restart your miner and see if this fixes it. You might have to try this a couple of times as sometimes it doesn’t work on the first attempt
  • If the above doesn’t work, contact Nebra support. They are able to fix this remotely.


What is Helium?

Helium is an IoT network that connects devices like dog tags, environmental sensors, bike trackers and more. It consists of gateway devices or hotspots connected to one another over the internet. Data from IoT devices is transmitted to hotspots or Helium Miners and then across the Helium network. Hotspot owners are rewarded with tokens called HNT for hosting mining devices in their homes or on their property. The less dense an area the higher the potential for token earnings. Consequently placing a miner in downtown Manhattan will not earn the host a lot. 

How to mine Helium?

In order to mine Helium you need dedicated hardware called a Helium hotspot or miner. There are many hotspot vendors including Rak, Nebra and others. The hotspot is like a wireless access point that is used to communicate with sensors and other hotspots. It is also connected to the internet over Ethernet or Wi-Fi.

Helium devices and the network are very new. Furthermore, the network is growing very rapidly and often runs into technical issues. We have attempted to document our troubleshooting procedures in blog posts.

What is the Rock Pi Miner?

The Rock Pi miner is the second generation miner from Nebra with the following specifications

Technical Specifications

SpecificationRockPi Indoor Hotspot
Dimensions94x70x53 mm (Excluding Antenna)
Power Requirement12V 2.5A USB-C
Maximum TX Power24-27dBm
Network Connectivity1GBit Ethernet, 2.4GHz Wi-Fi, Bluetooth 4.2
Antenna ConnectionRP-SMA Female
Rated Ambient Temperature20-30 degrees Celsius
Base SOMROCK Pi RK3399 Processor
CPU SpecificationDual Core Cortex A72 1.8 GHz and Quad Core Cortex A53 1.4 GHz
High Endurance Storage32 GB
Some of the most notable differences between this miner and the 1st generation miner (which I have) is the updated W-Fi and the external Wi-Fi antenna. This enables better network coverage relative to the older system where the Wi-Fi antenna is embedded in the system.

The USB-C power connector is a new feature as well. I lost one of my power adapters while moving the miner and it was challenging to find a replacement. The USB-C is easier to replace.

There are many similarities between the first and second generation of Nebra miners. It is very disappointing that the Wi-Fi connectivity hasn’t been upgraded to include the 5 GHz band. Instead connectivity is only on the 2.4 GHz frequency band. This is a deficiency relative to other miners like the Rak.

Other Helium Troubleshooting Guides: