I am getting this too.
Everything about my connection is fine, and I get no other drops anywhere else. It's just SL that works fine for a while and then suddenly will drop entirely. It doesn't even show packet loss or anything during the period where I can tell I'm getting disconnected, which is usually a minute or two. It only finally shows the connection being dropped as the "sorry you were logged out" message pops up.
I've tried everything I can think of, like port forwarding, router resets/reboots, changing settings, etc, etc. Nothing seems to work. I saw a post about Netgear routers and I recently bought one of those (Netgear D600) but this really only seems to have started in the past two weeks, and I've had the router since January.
Firestorm 5.0.1 (52150) Dec 10 2016 14:44:37 (Firestorm-Releasex64) with OpenSimulator support
Release Notes
You are at 193.6, 92.7, 1,894.5 in Mega Empire located at sim10619.agni.lindenlab.com (216.82.52.181:12035)
SLURL: http://maps.secondlife.com/secondlife/Mega Empire/194/93/1894
(global coordinates 123,842.0, 429,405.0, 1,894.5)
Second Life Server 18.02.12.512536
Release Notes
CPU: Intel(R) Core(TM) i7 CPU 950 @ 3.07GHz (3073.63 MHz)
Memory: 16376 MB
OS Version: Microsoft Windows 10 64-bit (Build 16299)
Graphics Card Vendor: NVIDIA Corporation
Graphics Card: GeForce GTX 750 Ti/PCIe/SSE2
Windows Graphics Driver Version: 23.21.0013.8813
OpenGL Version: 4.6.0 NVIDIA 388.13
RestrainedLove API: RLV v3.1.4 / RLVa v2.1.0.52150
libcurl Version: libcurl/7.47.0 OpenSSL/1.0.1i zlib/1.2.8
J2C Decoder Version: KDU v7.8
Audio Driver Version: FMOD Ex 4.44.61
LLCEFLib/CEF Version: 1.5.3-(CEF-WIN-3.2526.1347-32)
LibVLC Version: 2.2.4
Voice Server Version: Vivox 4.6.0017.22050
Settings mode: Firestorm
Viewer Skin: Firestorm (Grey)
Font Used: Deja Vu (96 dpi)
Font Size Adjustment: 0 pt
UI Scaling: 1
Draw distance: 128 m
Bandwidth: 3000 kbit/s
LOD factor: 4
Render quality: High (5/7)
Advanced Lighting Model: Yes
Texture memory: 1024 MB (1)
VFS (cache) creation time (UTC): 2017-2-25T4:30:48
Built with MSVC version 1800
Packets Lost: 0/2,948 (0.0%)
March 14 2018 15:02:11 SLT