Sonos is a huge disappointment

Human bodies are a great device for blocking wifi signals. A wired setup would work far better. 
 

A system that did work but now doesn’t is probably experiencing wifi interference, which can be caused by a number of factors. Environments change, unfortunately, and so does wifi reliability. And the demands that Sonos makes of a network - to provide a continuous stream of synchronised data - is far greater than, say, sending a file to a printer. 

You could get adapters and wire your Eras or go with the Pro version intended for your situation.

https://www.sonos.com/en-us/shop/era-100-pro-black

Getting them to work wireless is also an option but likely not your optimum solution.

so why did it work ok for the first few months? 

and why not anymore? and why did i have to configure the speakers again (and again)?

no, i dont believe this for a moment. 

also, i have a streaming set up from another brand at home. much older. but way more reliable no problems to connect. 

sonos is great at marketing, but the otherweise they just suck - and i am not the only one with that opinion. 

“Human bodies are a great device for blocking wifi signals.” lol thats totally exaggerated and quite franky bs

Bring your older streaming setup that works at home to the studio, and try the Sonos at home?

There are numerous reports describing systems that worked fine until the space filled with bodies. This has resulted in disappointing wedding receptions and parties. Placing WiFi access points and speakers above the crowd will minimize the risk.

If you can tell us about your network, that would help users here to give suggestions for a fix, if that is what you desire.

From what you have described, it sounds like you have issues with your network/router that is causing your connection issues. Have you tried rebooting your router/network as well?

These issues can also be caused by the speakers being too far away from your router.

I have an Era 100 that sometimes looses connection, but that is because its the furthest speaker from an access point. I have just finished running an ethernet cable from my network to the speaker, and will be testing it in the coming days. This is something you should also consider doing.

You don’t seem to beat about the bush in your statements: here’s my blunt response. 
 

As I said in my first reply: environments change. So much electronic equipment everywhere can cause interference. So I stand by my statement that just because it worked for a few months, it’s no guarantee to continue working. 
 

As far as  your comment that you have to “configure the speakers again (and again)”, this is one definition of stupidity: doing the same thing over and over and expecting a different outcome.

You’ve had suggestions put forward to help you towards a fix. Whether you wish to follow any of those suggestions is for you to decide. But without trying them, how can you be so sure the suggestions are invalid? 

If by reconfigure you mean factory reset then the reason you have to keep doing it is because it does not fix the problem. That is true for almost every problem, factory reset may make it disappear for a short time but rarely fixes anything.

If it was working and now isn't look to your local RF environment or your networking gear. If it was a Sonos update issue a lot more folks would be complaining.

I would consider the possibility of the people in class (or elsewhere?) possibly consuming your WiFi with their devices, maybe just 1 or 2 initially, but that has increased over time as they have shared the details. Some of the people in class may have hotspots enabled on their phones. New neighbours to studio installing/changing their WiFi.

“Something went wrong. Try again later.” (C)

That’s the “definition of stupidity” and the eternal mantra of the modern “tech”, all rolled into one. 😏