Migration from Sonoff ZBDongle-P to SLZB-MR1U – unstable network, worse performance

Hardware
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I want to share my experience migrating from a Sonoff ZBDongle-P to an SLZB-MR1U and see if others have seen similar behavior.

Previous setup (rock solid)

  • Raspberry Pi
  • Sonoff ZBDongle-P (USB extension cable to avoid interference)
  • Ember firmware
  • Zigbee2MQTT

This setup ran for years without issues. As long as I followed the Zigbee2MQTT release notes and firmware recommendations, everything was stable. No performance problems, no instability. ~40 devices (mostly Hue lights, plus some Tuya, IKEA, Gledopto and Wiser).

Why I migrated

I’ve read a lot of positive feedback about SMLight products. The idea was:

  • Replace the Raspberry Pi
  • Run Zigbee2MQTT on my NAS (where I already host other services)
  • Use SLZB-MR1U as coordinator

Migration process

For the first migration I used Radio 1 (EFR32MG21) on the MR1U.

I followed the SMLight migration guide and everything initially looked fine:

  • All devices came back online
  • Fully controllable from Zigbee2MQTT and Home Assistant

After issues started, I switched to Radio 2 (CC2652P7) instead. The behavior was exactly the same, no improvement, equally unstable.

Problems started after a few minutes

  • Devices began going offline
  • Devices became unresponsive

I powered everything down from the electrical panel, waited, powered up the coordinator first, then devices.

They came back online… but then:

  • All lights started blinking
  • Long flickers, repeated blinking
  • Complete “storm” across ~40 devices

Total chaos.

Recovery attempts

I powered everything off again and reintroduced devices slowly:

  • 2–3 devices at a time
  • Waited ~20 minutes between batches

Some devices (mainly Hue and IKEA lights) dropped completely and required:

  • Multiple power cycles
  • In some cases factory reset
  • Remove from Zigbee2MQTT and re-pair

Eventually, I got everything back online and stable.

Temporary stability… then chaos again

It ran mostly fine for a few days.

  • Some failed pings in logs
  • Devices still responded to commands

Then suddenly (a few days later):

  • All lights started blinking again
  • Long flickers, frenzy behavior

This happened right at bedtime, so I had to cut power manually to stop it.

LQI behavior

  • After factory reset and re-pair, LQI is very good
  • After some time, LQI drops significantly
  • Some devices eventually go offline

This pattern repeats with the same devices.

Current status

The network is technically “up”, but performance is much worse than before:

  • Low LQI across many devices
  • Failed pings
  • Devices randomly offline
  • Slower responsiveness

Compared to my previous ZBDongle-P setup, this is clearly worse.

What would you do?

At this point I’m unsure how to proceed:

  • Completely start from scratch (fresh Zigbee network, new network ID, re-pair all devices cleanly)?
  • Or ditch the SLZB-MR1U and go back to the Sonoff dongle?

Has anyone experienced similar instability with the MR1U (on either radio)?

Any advice before I go through another full rebuild would be appreciated.

2

Update (if anyone else struggling with the same issue find this post):
After days of trying to fix the network after the migration I decided to build it from scratch with the MR1U as the coordinator (new network ID’s), factory reset all devices and paired them to the new network. → Rock solid again (based on a few days testing), maybe even a bit better responsiveness compared to before. So I can not blame the MR1. I still don’t know what the root cause for the instability was though.