Just an FYI There is already a write up on mapping your ZigBee network by @JohnR - FAQ: Mapping your ZigBee network with Digi's XCTU
Also mapping your network is great if you just really like spending your time geeking out on these things like many on here but it’s not really necessary in the end you will end up going through the work just to likely confirm you need proper repeaters not Bulbs. Lowe’s iris 3210-l is a popular choice here due to number of zigbee devices it can repeat for and reasonable cost + acts as a Zwave repeater. Although many report Zwave repeater doesn’t seem to function. I haven’t really looked into whether it’s repeating for me because I only have 3 Zwave devices. You could also try repositioning the hub orientation or moving it to a central location. If you don’t want to spend money on repeaters that’s the first step.
One final thing about Bulbs is that in addition to typically acting as poor repeaters it is common for people out of habit to power off Switches for the circuit. Once that happens your zigbee mesh strength is going to be out of whack assuming they were repeating properly. All my lights are automated to turn and off yet no matter how often I remind friends and family there is no need to power them off it still happens regularly. Sure there are ways to mitigate this like disconnect the switch and hardware the circuit I prefer to still have the switch just in case bulbs become unresponsive. Also I believe it goes against building code to do so. The other option is to put a switch guard which helps but doesn’t stop the issue.
I don’t claim to be an expert but have learned from my own experience that just because everything is stable for a period of time that can suddenly change. Everything was working great for me for 9 months after buying ST. I signed up for a hub beta and not long after zigbee devices started randomly going offline usually pulling or replacing the battery fixed the problem temporarily. I initially resisted buying repeaters thinking it had to be related to the beta since everything had been working fine. After a couple months of doing this and beta being finished I finally broke down and bought a couple Lowe’s repeaters and no more problems.