90% LAN Throughput Degradation

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massis's picture
90% LAN Throughput Degradation

I'm having random LAN throughput degradation problem with my r6300v2 router.  Rebooting the router *sometimes* fixes the problem for several minutes or few hours.   During the short periods that the router is working properly, I can transfer large files (20-50GB) at 70-110MBps.  However, once the slowdown occurs, the throughput drops and stays at 3-11MBps.  

It’s important to note that this problem does not occur with the Netgear f/w.

I use a Netgear r6300v2 router with DD-WRT v3.0-r29300M kongac (03/30/16) firmware on a Gigabit LAN. The only features enabled on the router are DHCP and DNSMasq.  The LAN consists of wired and wireless Windows machines (no p2p software) and printers.  Thankfully, this problem does not affect my Internet connections (200Mbps/20Mbps via TWC).

For testing, I've ensured that there is no other activity on the network or source and destination machines.  I’ve tried the following startup setting that I’ve found in other posts.  

## Set state timeouts
echo 600 > ${prefix}_generic_timeout
echo 30 > ${prefix}_udp_timeout
echo 60 > ${prefix}_udp_timeout_stream
echo 1800 > ${prefix}_tcp_timeout_established
echo 120 > ${prefix}_tcp_timeout_syn_sent
echo 60 > ${prefix}_tcp_timeout_syn_recv
echo 120 > ${prefix}_tcp_timeout_fin_wait
echo 120 > ${prefix}_tcp_timeout_time_wait
echo 10 > ${prefix}_tcp_timeout_close
echo 60 > ${prefix}_tcp_timeout_close_wait
echo 30 > ${prefix}_tcp_timeout_last_ack
## Set buffer sizes
ifconfig eth0 txqueuelen 1
echo 262144 > /proc/sys/net/core/rmem_max
echo 262144 > /proc/sys/net/core/wmem_max
echo "4096 87380 262144" > /proc/sys/net/ipv4/tcp_rmem
echo "4096 16384 262144" > /proc/sys/net/ipv4/tcp_wmem
echo 1000 > /proc/sys/net/core/netdev_max_backlog
echo 16384 > /proc/sys/net/ipv4/netfilter/ip_conntrack_max
echo 16384 > /sys/module/nf_conntrack/parameters/hashsize

Using other "txqueuelen" values (0-100) makes no difference.

I'm essentially praying that netowrking experts here can provide specific instructions on how to resolve this problem.  My only alternative is to revert back to the factory f/w and run DNS on a desktop PC--a choice between unacceptable network throughput or flaky DNS.