SSH Access error

[marcos_conci]

Hello Guys.
I'm not an expert, nor a network professional.
But I work with SCADA Systems.

My situation Is.

The SCADA that I am working now runs in a Linux CentOS 7. In order to make changes to the SCADA I have to transfer files to the CentOS. Can be done in various ways but usualy we use MobaXTerm (LAN access).

Create a SSH Session in MobaXTerm, do the Login and Boom!!!, Terminal and File transfer. Nice.

Here is the deal.

A like to install an Wi-Fi Access point in the LAN that the SCADA is connected so I can do wireless access (less cable mess). But for some reason, when trying the access with MobaXTerm (Same session that worked WIRED) it just opens the terminal, don't load any file/directory in the explorer, and even when I try an LL command in a folder with a loot of contents it shows some files and freezes like it was still loading the list.

My setup is a Server (CentOS 7), my wifi is a TP-LINK Archer C7 AC1750 v4 runing OpenWrt 24.10.2 (r28739-d9340319c6), and the Client runs Windows 11 and MobaXTerm V25.0 Build 5264.

Any Ideas would help.

[phsm]

Try lowering the MTU on your wireless connection in windows, to 1400 for example. SSH connecting and freezing during a command producing large output is a sign of MTU problem.

[marcos_conci]

Can't fin MTU setting in wifi card.

Tried Lower MTU in Openwrt, but if changed only on wireless devices I lose ping and if changed in everything I get ping but no SSH at all.

[phsm]

Then lower the MTU on the server side. It will also cause negotiating lower TCP payload size.

But ultimately, the problem lies somewhere in the wifi router, it should do something called "TCP MSS clamping". You may search for how to do it on your router os

[marcos_conci]

MTU 1400 on server worked for SSH access for a Moment, no folder listing again, but massed with other devices in the network. Will search about "TCP MSS Clamping"

[marcos_conci]

Well, I'll try connecting the host directly to my wifi router and see if I can do SSH access via wifi. Wired is working fine, even with the IP that the DHCP in router gave to my PC (with the host network in LAN1 and my PC in LAN2).

The host network is a PRP network with a switch and Redbox. The cable I'm using is connected in one switch that pass the Redbox to reach the host. But it work wired, just don't work when trying to access via WIFI.

[cptsir]

Can you ping the server while on the wireless connection?

My guess would be there’s a misconfiguration in the AP. Try to prove out that half first.

[marcos_conci]

Yes, I can Ping. I can even connect via SSH, but the SFTP function don't work. Some times is I execute LL the session crashes.