Why chess.com servers are so bad ?

I have a great internet speed, i'm playing from a pc with very good interet, yet the chess.com servers fail very often. and i mean often. 

whats going on on this server ?

Right now? There is a global issue that has caused a spike in internet traffic in general and that holds for most entertainment sites as well. With increased traffic in general, your traffic from your client to the chess.com server is competing with other traffic on the internet, so the farther you are from the site's Live server (how many pieces of equipment you have to travel through) the more latency you are likely to see and the more chances to have issues with connectivity.

Add to that, there are advertisements, which may introduce lag.

There are some things you can do to minimize issues on your end.

https://support.chess.com/article/213-how-do-i-fix-my-disconnect-lag-issues

You won't be able to solve all the issues, especially now that traffic is so much higher but it can help. I played yesterday on my cell phone, using the mobile website (not app) and didn't have any issues with either of the two events I played in.

i also dont understand it, it's pretty frustrating to have many games end with a disconnect...

I think it’s fine. How else I get to hyperbullet rating of 1500 and beating my opponents under 20 seconds countless  times ?

It's really bad. It's not my internet connection either because Lichess works perfectly.

The path the traffic takes from your client to different sites only shares a small section. So, there can be be issues between you and the chess.com servers that does not exist between you and another site. However, there can also be issues client side that can impact things, especially when there are differences in coding, traffic flows/data (such as ads), and how each site handles lag and disconnects.

why when i start the game, does the server work fine. yet 4 or 5 moves into the game, all of a sudden i'm down to 1 bar and it takes 45 secs to make every move???!!!!

This issue is still happening. I can do online zoom and microsoft team meetings all day without issues, including streaming and countless other internet stuff, but I keep getting timed out of chess games. I would at least like this issue to be recognized on their end unless it really is just lots of people who only have internet issues on chess.com

There can be a lot of different things that cause connectivity issues. The link in post 2 gives information on things that can be done to minimize issues. 

Play hyperbullet. I have no problems playing hyperbullet.

https://support.chess.com/article/213-how-do-i-fix-my-disconnect-lag-issues

I am pretty confident chess.com has major problems regarding connentivity. There is no other explanation, why in 4 player game all the players disconnects at the same time in every second game lately. It frustrates as a paying customer to suffer chess.com to practice running a server. :/

Huh, I haven't had any connection issues in months... 

Today for the second time the server is down 

https://www.chess.com/blog/CHESScom/chess-is-booming-and-our-servers-are-struggling

I'm pretty close to giving up on chess.com and moving to lichess.  This has clearly been a problem for years that chess.com is not motivated to fix.  Every other game I lose due to disconnects or lag and my internet and computer both work just fine.  What is the point of playing when I can't finish half my games?

It's not internet speed that matters for a game like chess, but stability - video and audio streaming services can download stuff ahead of time so if the connection drops out for a moment, the person never notices. Chess doesn't have the same volume of information, but it's time critical - you need your internet to send your move when you make your move.

If it's been happening to you "for years", it's probably not this most recent lack of server capacity but an issue between with your internet connection to Chess.com's server. lichess' servers are in a different geographic location so you might not have the same problems with them - or maybe you might - and Chess.com will be running on distributed servers in the very near future which may also alleviate this problem. Or maybe it won't, if the instability is close enough to your end of things.