If you have DNS errors trying to log in, or simply get disconnected during or immediately on log in, try flushing your DNS cache; how to do that is explained here for Windows, Linux, and Mac Snow Leopard. For Mac Lion and Mountain Lion, see here. For Mac Mavericks, see here.
if this doesn't help, then try setting your DNS to Google: Google Public DNS
Should using Google as a DNS not work for you then see here for alternate servers, or grab DNS Bench to help you locate one.
See below for other causes which are specific to your operating system.
DNS errors might be caused by anti-virus software; see this page for more on that.
Various Troublesome Behavior
This is a collection of symptoms, all or some of which you may be experiencing together. If you have them on Firestorm, then you will experience them on other V3 viewers (like the official LL viewer) but not on V1 viewers (like Phoenix). The fix is very easy but not especially intuitive.
Crashing or getting logged out on all or most teleports;
Friends list and groups list not loading;
Inability to view any mesh;
Inability to view “About Land”;
Inability to open notecards;
SLVoice does not connect.
How to fix this:
On your Mac, open System Preferences and go to Network > Advanced > DNS
Hit the plus button (+) and type in the numbers 220.127.116.11.
Hit the plus button (+) and type in the numbers 18.104.22.168.
If you live in Asia or Australia, you will need to use the following numbers instead of those just listed: 22.214.171.124 and 126.96.36.199. Even those in other parts of the world might find this pair to work better, so if you complete the process and find no change, repeat it with this set.
Close the System Preferences and restart your viewer.
What this does:
This process adds GoogleDNS and/or OpenDNS to the DNS
servers your Mac attempts to use. There is no need to delete the numbers already there; if the system cannot work with them, then it will go down the list until it finds one it can.
The issue is related to Linden Lab JIRA VWR-26759
. Any additional information we know about it is on that JIRA.
If you would like to read about either of these DNSes before adding them to your system, you can visit their pages here for Google
or or here for OpenDNS
. You may have another set you would prefer to try besides these two, but as you can see on the Linden Lab JIRA, the changes in DNS
are the only known fixes for this set of problems.
Acknowledgement to Queen Kellee for the way the step-by-step instructions were written.
"DNS Could Not Resolve the Host Name"
If you use Hands Off! security software, try uninstalling it. So far, the evidence that this software may be related to this problem is anecdotal, but it is something to try.
Certain proxy redirectors external to the viewer can cause “DNS Could Not Resolve the Host Name” failure at login.
ProxyCap proxy redirector is known to cause this.