Your GO Plus is not connecting to Pokémon GO. It is having problems and not functioning? This is the downside of the new update, which actually brings two significant changes.
What is wrong with the GO Plus? Reports from players about issues with the GO Plus have been increasing for several hours. The reason for this is the new update that players already installed on their smartphones. With the new patch to version 0.173.0, there are mass transfers and easier power-ups. However, the connection problems with the “GO Plus” accessory are dampening the mood.
GO Plus not connecting – What are the issues?
This is what players are saying: On Twitter, Niantic operates an account that occasionally addresses the support of Pokémon GO. Changes and problems are discussed there. Among the latest posts, messages like “Fix GO Plus” are increasing.

In our Facebook group for Pokémon GO, you can also find trainers repeatedly reporting problems with the latest update 0.173.0 and the GO Plus.
What does Niantic say about this? The developers at Niantic are aware of the problem and are already working on a solution. Officially, it is stated on Niantic’s support website:
The “Pokémon GO Plus” and “Poké Ball Plus” devices are not recognized by the app on Android devices and cannot connect to the game.
The error will be fixed in a future update.
Source: Niantic Support website
When this update with the bug fix will be released is currently unclear.
2 cool new features in the update
What changes for you: Besides the problem with the GO Plus devices, the update 0.173.0 also brings good changes.
Event Pokémon can now be sent as mass transfers. This is a request that trainers have been expressing for years. Because costumed Pokémon were previously not eligible for mass transfers and had to be sent individually. This took much more time than sending several Pokémon at once.

You can now distribute power-ups in one go. This means that during a power-up action, you can spend multiple candies and stardust to perform multiple boosts in one action.
This power-up change was one point of our 10 simple features that would greatly improve Pokémon GO.