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Shelly Pro 3EM with Anker Solix (error 35) or Marstek Venus: check the connection and understand the "phase_sequence" warning

Shelly Device: Shelly Pro 3EM (also Shelly 3EM) as the meter for an Anker Solix Solarbank or Marstek Venus · Updated · Auch auf Deutsch

Firmware as of: Gen2+ as of 26 Oct 2026 per the official changelog: stable 2.1.1, 2.0.3 or 1.7.6 depending on the device (2.1.0 added NILM for energy meters). "RPC over UDP" can be set in the web interface since 1.4.0; 2.0.1 fixes a bug with the "udp_in" channel type. Anker and Marstek firmware: see the respective app.

Generations: Gen2/Plus

What you see:

  • Anker Solix: the Anker app reports error 35 ("wrong meter connection") or the Solarbank doesn't regulate to zero feed-in with the Shelly meter.
  • Marstek Venus: the battery doesn't find the Pro 3EM or shows 0 W; the CT icon in the Marstek app doesn't turn green.
  • Pro 3EM: the web interface shows the warning "phase_sequence".

What it means: The battery reads the grid power from the Shelly over your home network (Anker via the Shelly Cloud, Marstek locally via UDP). Errors come from unsupported models, network problems, wrong settings, or a wrong measurement direction or phase assignment. Only the last one may require work in the distribution board, and that's a job for an electrician.

Cost: €0 / CHF 0 for all settings. An electrician costs money if rewiring is really needed.

Step 1: Check supported model and firmware 5 min

Anker: according to Anker's official guide:

  • Supported: Shelly 3EM and Shelly Pro 3EM with Solarbank 2 Pro, 2 Plus and 3 Pro.
  • Explicitly not supported: 3EM-63T Gen3, Pro 3EM-3CT63, Pro 3EM 2x50A.
  • Requirements: current Anker app, Solarbank firmware with support for third-party meters, and the Shelly must already be set up in the Shelly Cloud. Anker says the feature is rolled out gradually; if the update doesn't appear, Anker names support@ankersolix.com.

Marstek: the guide from the Dutch Marstek distributor covers the Pro 3EM for the Venus C/E.

Step 2: Check the network 10 min

  • Shelly and battery on the same Wi-Fi, not the guest network. In the Photovoltaikforum a FRITZ!Box guest network blocked the communication.
  • FRITZ!Box: enable the option that lets active Wi-Fi devices communicate with each other (exact menu name varies by FRITZ!OS version).
  • Signal: a Pro 3EM in a metal distribution board often has poor Wi-Fi. According to a community blog on error 35 this is a common cause; a too-weak signal at the Marstek also prevented the connection for one owner. Check the signal in the Shelly web interface (see Shelly offline and Wi-Fi). The Pro 3EM also has a LAN port; running a network cable inside the distribution board is a job for an electrician.

Step 3a – Anker: reconnect the meter (10 min)

Per Anker's guide: Anker app › Add device › Third-party device › Shelly Cloud › log in with your Shelly account › add the meter. (Menu labels translated from the German guide.)

If the connection is gone after a Shelly update: in the Shelly Community, a Solarbank 3 Pro owner reported lost communication after Shelly firmware 1.7.0; removing the meter in the Anker app and adding it again helped. A Shelly administrator pointed out that third-party integrations are maintained by those third parties.

For error 35, commenters on the community blog also report a complete re-setup (delete all devices in the Anker app, reset the Solarbank, add again). That's an owner report, not official guidance; ask Anker support first.

Step 3b – Marstek: "RPC over UDP" on port 1010 (10 min)

Per the Marstek guide (Netherlands) and reports in the Photovoltaikforum:

  1. In the Shelly app on the Pro 3EM: gear icon › Networks › enable RPC over UDP, enter port 1010.
  2. Reboot the Shelly.
  3. In the Marstek app select "Shelly Pro 3EM" as meter type and check the connection until the CT icon is green.

Notes from the forum: pairing via Bluetooth didn't work; the connection runs over the network. One owner additionally had to enter the router IP with ":1010"; port 2220 didn't help. Some Venus E Gen3 owners still found no connection – the sources have no confirmed fix for that.

Step 4: Check readings without rewiring 10 min

Look at the power per phase in the Pro 3EM web interface. According to Shelly support:

  • Negative power although you're drawing power: a current transformer is probably reversed. Instead of rewiring, use "Reverse CT measurement direction" in the web interface.
  • Zero on one channel: the CT may be on the neutral conductor. An electrician checks that.
  • According to the Shelly knowledge base, below 30 VA per channel no energy is counted ("No load threshold" notice).

For error 35, Anker's official error description (quoted in the community blog) names: CT at the house connection and not on a branch circuit, direction from the distribution board towards the grid, voltage and current on the same phase, good network at the meter. Changing any of that is work in the distribution board: electrician.

Step 5: The "phase_sequence" warning 5 min

  • According to the Shelly knowledge base, the Pro 3EM detects the phase sequence from the voltage zero crossings. If the phases arrive as A→C→B instead of A→B→C, it reports "phase_sequence" when the detection option is enabled.
  • The German-language Shelly forum explains: no clockwise rotation across A–C, metering itself is not affected, and detection can be turned off in the channel settings.
  • For a wrong phase assignment, Shelly support names checking the phase-to-CT assignment and the order A→B→C; a qualified person should check this.

Important: ignoring the warning only helps if voltage and CT on each channel belong to the same phase. If they're mixed up, the per-phase readings are wrong and the battery regulates wrongly. An electrician sorts that out.

When to contact support or an electrician

  • Electrician: CTs or phases have to be moved, a channel shows 0, or the phase rotation should be measured.
  • Anker support: error 35 persists after steps 1–4, or the third-party option is missing in the app.
  • Marstek support or retailer: the Venus doesn't find the Pro 3EM despite port 1010.
  • Shelly support: the Pro 3EM itself measures implausibly or is unreachable.

Shelly support (official)

Sources

FAQ

Which Shelly meters does the Anker app support?

According to Anker's guide (at the time of writing), the Shelly 3EM and Shelly Pro 3EM with Solarbank 2 Pro, 2 Plus and 3 Pro. Explicitly not supported there: 3EM-63T Gen3, Pro 3EM-3CT63 and Pro 3EM 2x50A.

Is the "phase_sequence" warning dangerous?

According to the Shelly knowledge base, the Pro 3EM shows it when the phases arrive in the order A→C→B instead of A→B→C and detection is enabled. The Shelly forum explains that it doesn't affect metering and can be turned off in the channel settings. Whether the phases should be connected differently is for a qualified electrician to decide.

Why does the Pro 3EM show negative power although I'm drawing power?

According to Shelly support, a current transformer is usually mounted the wrong way round. Instead of rewiring, the measurement direction can be reversed in the web interface ("Reverse CT measurement direction").

Which port does the Marstek Venus need?

The Marstek guide from the Netherlands names "RPC over UDP" with port 1010 in the Shelly app. In the German Photovoltaikforum, owners report that this worked for them, but some with a Venus E Gen3 still got no connection.

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