There's several possible kinds of issues:

1. Client issues. Please report them to your client bug tracker (for example, qTox bug tracker, Toxy bug tracker or uTox bug tracker).
2. Packaging issues. If you have troubles with your Tox repository, please report them to the infrastructure mailing list at infrastructure@lists.tox.chat, or directly to the administrator at admin@tox.chat
3. Issues with the Tox core library should be reported to the toxcore bug tracker. Do not report an issue to toxcore if you are not entirely sure whether it's a core issue. Instead, report it as a client issue.

There are antiviruses that report Tox as false positive. If you did get Tox from official Tox website, and your antivirus causes problems and is not in the list please say that antivirus causes problems. Additionally, you could report to your antivirus makers that Tox is reported as false positive when it should not be.

Unfortunately, current Tox groupchats don't support saving, moderation or joining without invite. The New groupchats, which are still in development, will fix these issues.

tl;dr: Your network connection deserved to be killed.

Explanation: Sometimes you will have a router or some other network device which does not want to work well with Tox. In fact, it may outright refuse to work at all, “dying” at your hands.

<irungentoo> the routers dieing is caused by too many connections
<irungentoo> some idiotic routers treat one UDP packet sent to an ip/port as one connection
<irungentoo> and keep track of it
.
.
<irungentoo> and the reason why hole punching doesn't work very well on newer routers

There isn't a lot that could be done about it, but there is a workaround - you can disable UDP in your Tox clients and see whether it would help.

Tox messaging of all kinds requires both parties to be online at the time the exchange takes place. Some clients implement pseudo-offline messages, where they save a message and schedule it for delivery the next time you and your friend are both online. This is safe, but it still requires both parties to be online. The developers are working on an implementation of offline messaging which works without compromising the security, privacy, and decentralization that Tox promises.

If you use a client which allows you to schedule pseudo-offline messages, in order for them to be delivered you have to both be online. If you are the person who scheduled the message, staying online at your computer will help maximize the chance you will be online at the same time as the intended recipient, but leaving your computer or device unattended with messages visible on the screen is a potential security risk to somebody who just happens to walk by.

Tox messaging of all kinds(including Friend Requests) requires both parties to be online at the time the exchange takes place. Try to make sure that both computers are connected to the network when the friend requests are made.

In order for a friend request to complete:

1. Other side has to be online to receive the Friend Request.
2. Other side has to accept Friend Request after receiving it.

If you are sure that other side was online when you sent the Friend Request, and they did not receive it, please report it.