Bulbs are one of those “maybe, maybe not” issues. See the bulb FAQ ( this is a clickable link)
And the GE links in particular have their own firmware issues and tend to drop off the network more than any other zigbee brand, so I definitely wouldn’t start with those. Eco-smart or Cree would be a better one to try.
All of that said, in the US many community members like the Lowe’s iris pocket socket. It’s a reliable zigbee repeater.
Whatever repeating device you choose, after you have it paired and in place, you want to get the fan to update its neighbor table so it will use the new repeater.
To initiate this process, you do a “network heal.” For zigbee devices, that means taking the hub off power (including removing any batteries) and leaving it off power for at least 15 minutes. Leave the other zigbee devices on power. This will cause the other devices to go into “panic mode” because they can’t reach the hub. Then when the hub comes back on power all the devices will rebuild their individual neighbor tables. This process can take a little while, so you may not see the full effect until the next day.
Eco-smart or Cree would be a better one to try.