Wi-fi network partially falls off + how to increase the speed on TP-Link Archer C7?

Question

network hardware

There is a router with support for 802.11ac up to 1750 Mbps TP-Link Archer C7 , hardware version v2, standard firmware.
There is an ASUS 750JX laptop , in which the wi-fi module is replaced with Intel® Dual Band Wireless-AC 7260 , which also supports 802.11ac, but already 867 Mbps.
Problems three:
1. It is impossible to receive speed above 300 Mbps in any way. I would like at least 500-600. The laptop is connected to 5GHz.
2. Some devices connected via 5GHz periodically fall off the network. For example tablet Samsung Galaxy Note 10.1 and iPhone 5S . Software restart wi-fi on the device helps. But at the same time HTC One, as well as the above laptop does not suffer from such a problem.
3. The wi-fi signal at the same 5GHz is very weak. Through 1 wall it almost does not catch on the tablet. At the same time, on the same tablet and on the old TP-Link TL-WR1043ND router, the signal was on "all sticks".
The router operates in two bands - 2.4GHz and 5GHz. Disabling 2.4GHz does not solve problems.
In which direction to dig?

Answer 1

Characteristics and description
General characteristics
Type
Wi-Fi router
Wireless
standard 802.11n, frequency 2.4 GHz
MIMO support
yes
Max. wireless connection speed
300 Mbps
Reception/transmission
Information security
WEP, WPA, WPA2
Transmitter power
20 dBM
Access point/bridge options
Switch
4xLAN
Port speed
1000 Mbps
Number of USB 2.0 Type A connectors
1
Router
Firewall (FireWall)
yes
NAT
yes
SPI
has a
DHCP server
Yes
Dynamic DNS support
yes
Demilitarized zone (DMZ)
yes
Static routing
yes
VPN
VPN pass through support
yes
PPTP support
yes
L2TP support
yes
IPSec support
yes
Antenna
Number of external antennas
3 x 3 dBi
External antenna type
removable
Monitoring and configuration
Web interface
yes
Optional
Dimensions ( WxHxD ) 200x28x140
mm