Build a reproducible example
Official help associates 277 with the client's network connection on computers, Macs, and mobile devices. For your verification, save the full text, game name, time and device. Login twice to the same project, then try another one. If the disconnect appears only after a specific action, write it down separately. One successful login does not indicate that the problem has been eliminated. Another error at the next launch requires a separate analysis: compare the full messages, and not just the fact of the crash.
Test another network without changing settings at the same time
The Roblox instructions provide a comparison with another available Internet connection. Keep the game, device and launch method unchanged, changing only the network. For each attempt, write down the result and time until disconnection. If the problem occurs exclusively on one network, provide this information to your ISP or administrator. If 277 also appears on another network, do not declare the first network OK: the test only narrows the range of reasons. No need for random port settings from other people's comments.
Phone: application, restart and time
Close Roblox completely and restart your device. The mobile sections of the official help include checking the date and time, as well as reinstalling from the appropriate store. Before deleting the application, check access to your account. iOS uses the App Store, Android uses Google Play, Fire OS uses the Amazon Store. The force close menu varies by device. After each step, repeat the initial attempt; if you do everything at once, it will be difficult to understand what changed the result.
Computer and contacting support
For a computer, the official instructions include reinstalling the client; for Mac - also check permission to run Roblox. Additional actions with local data are described in the section of your OS. Old operating-system names in the help article do not prove those systems are supported today. In your Roblox Support request, add username, system, device, full message 277, game and results table: original network, different network, different project, restart. Clearly indicate at what stage the connection is broken, and do not pass off the completed test as the reason found.
Sources and checks
Guides are automatically translated from Russian; interface labels may differ. The Russian edition is the original.