Internet hangs when uploading or downloading via nextcloud

I tried testing after installing the cloud package.

The installed packages are pydio and nextcloud.

My server environment is Ubuntu 16.04.3, nginx 1.13.8 php7.1-fpm mariadb 10.2.

When uploading or downloading material via the cloud programs, the Internet connection is stopped or slowed down by other Windows PC connected to the same router.

What is the cause of the problem?

The router I am using is Asus RT-N66U. The firmware is using Meriln firm.
In the meantime, no matter how much data was downloaded through transmission, there was no such problem at all.
Nextcloud and Pydio have the same problem.

I’ll give you some information to help you answer.

2: enp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
link/ether 1c:1b:0d:27:1d:71 brd ff:ff:ff:ff:ff:ff
RX: bytes packets errors dropped overrun mcast
13023685979 12251507 0 0 0 14327
TX: bytes packets errors dropped carrier collsns
5641872084 10045040 0 0 0 0

Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Supported pause frame use: No
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Advertised pause frame use: Symmetric Receive-only
Advertised auto-negotiation: Yes
Link partner advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Link partner advertised pause frame use: Symmetric Receive-only
Link partner advertised auto-negotiation: Yes
Speed: 1000Mb/s
Duplex: Full
Port: MII
PHYAD: 0
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: pumbg
Wake-on: g
Current message level: 0x00000033 (51)
drv probe ifdown ifup

I solved the problem in the following way.

iptables -A INPUT -p tcp --dport 443 -m conntrack --ctstate ESTABLISHED -m hashlimit --hashlimit-above 9000kb/s --hashlimit-mode srcip --hashlimit-srcmask 32 --hashlimit-name inrate -j DROP
iptables -A OUTPUT -p tcp --sport 443 -m conntrack --ctstate ESTABLISHED -m hashlimit --hashlimit-above 9000kb/s --hashlimit-mode dstip --hashlimit-dstmask 32 --hashlimit-name outrate -j DRO