RTO888 wrote

Can i know eap 245 support how many device in radio 2,4Ghz  and Ghz ?

According to TP-Link specs an EAP245 can theoretically support 80-100 clients in total.

However, the maximum number of clients depends on many environmental influences. Of course, a »full house« will increase the latency as it is usual for any shared medium such as a wireless network. Naturally, total bandwidth is shared by all those clients, so the price to supply many clients is lower throughput, which also depends on the typical use pattern of your clients.

Some parameters which affect the maximum number of users are:

• Multi-SSIDs: the more SSIDs you have the more AirTime is needed for the beacon alone.
• WiFi rates: clients negotiating lower WiFi rates (e.g. due to obstacles, interferences, distance etc.) will acquire more AirTime to transmit data, too.
  Old clients which only support old rates will do so, too. It can help to limit available WiFi rates if all your client support newer standards such as 802.11n/ac.

2ms stable latency over a half-duplex shared medium for clients at a certain distance, in an urban area and with obstacles in LoS tot he AP?
Never ever:

$ ping 192.168.178.1
PING 192.168.178.1 (192.168.178.1): 56 data bytes
64 bytes from 192.168.178.1: icmp_seq=0 ttl=64 time=1.531 ms
64 bytes from 192.168.178.1: icmp_seq=1 ttl=64 time=2.967 ms
64 bytes from 192.168.178.1: icmp_seq=2 ttl=64 time=1.552 ms
64 bytes from 192.168.178.1: icmp_seq=3 ttl=64 time=2.075 ms
64 bytes from 192.168.178.1: icmp_seq=4 ttl=64 time=4.639 ms
64 bytes from 192.168.178.1: icmp_seq=5 ttl=64 time=3.014 ms
64 bytes from 192.168.178.1: icmp_seq=6 ttl=64 time=1.811 ms
64 bytes from 192.168.178.1: icmp_seq=7 ttl=64 time=1.411 ms
64 bytes from 192.168.178.1: icmp_seq=8 ttl=64 time=1.480 ms
64 bytes from 192.168.178.1: icmp_seq=9 ttl=64 time=3.167 ms
64 bytes from 192.168.178.1: icmp_seq=10 ttl=64 time=16.756 ms
[...]

64 bytes from 192.168.178.1: icmp_seq=24 ttl=64 time=6.455 ms
64 bytes from 192.168.178.1: icmp_seq=25 ttl=64 time=20.229 ms
64 bytes from 192.168.178.1: icmp_seq=26 ttl=64 time=1.544 ms
^C

--- 192.168.178.1 ping statistics ---
28 packets transmitted, 27 packets received, 3.6% packet loss
round-trip min/avg/max/stddev = 1.381/3.946/20.229/4.823 ms
$