EDIT 2: After trying the Lumiya viewer on a 4G network and doing a synchronised computer and network restart, everything seems to be working again.
Yesterday I've been getting this error message: "Darn. You have been logged out of Second Life. This region may be experiencing trouble. Please check your connection to the internet."
I'm using Blackdragon viewer, and every time I try logging in I'm unable to move or sit on in-world objects, but I can teleport to other areas and send/receive messages - until I'm forced to log out with the error message above. It usually takes less than a minute for my viewer to log me out of SL.
I tried clearing my AppData/Roaming folder, but that didn't fix anything, so I tried installing a fresh copy of Firestorm, but I'm still getting the same issue. Any help would be appreciated. EDIT: The computer is a model VN7-593G-75AG Acer Aspire V 15 Nitro running 64 bit Windows 10. The same issue applies to the official viewer. Pinging the server I connect to with CMD results in no lost packets.