{actor} created a new topic '...

I've been tearing my hair out to make this connection, without success.
My Celestron 4SE is the older type with the "serial" handset connector, not USB.
I'm trying to make the connection using the following connectors
a) this USB-DB9 adapter
b) Celestron's 93920 adapter

I have also seen the advice on INDI's Celestron Page which informs me that
"You must power and align your mount using the handset using any supported alignment method (e.g. SkyAlign). Without aligning your mount first, the driver will not connect to the handset."
I am following this procedure.

I infer that the USB-DB9 connector is good because I can see that connecting it creates a /dev/ttyUSB0 device in the file system that is not there prior to connecting it:

Prior to connection:

astroberry@astroberry:~ $ ls -al /dev/ttyUSB0
ls: cannot access '/dev/ttyUSB0': No such file or directory

After connection:

astroberry@astroberry:~ $ ls -al /dev/ttyUSB0
crw-rw-rw- 1 root dialout 188, 0 May 19 14:04 /dev/ttyUSB0

My settings are as in the attached screenshots. Perhaps you can spot something wrong there.

[
Yet, when I try to connect, it always fails:

2022-05-19T20:19:31: [ERROR] Failed to communicate with the mount, check the logs for details. 
2022-05-19T20:19:31: [ERROR] Serial read error: Timeout error 
2022-05-19T20:19:26: [ERROR] Serial read error: Timeout error

Another symptom which may or may not be significant is that if I keep the handset connected and connect the 93920 to the AUX port, the handset says "No Response 17 Press BACK to continue". I don't know if it's possible to connect both at the same time or if this message is significant, assuming I could have made a connection.

I am left with the suspicion that the most likely possibility is that the mount's firmware is not up-to-date as is mentioned on your Celestron page.
My firmware versions are as follows.

HC: NXS 5.25.4320
MC: 5.20 5.20

However, I am reluctant to change this merely on general principles, as it poses some risk of unrecoverable damage, without some assurance that it's likely to help.
Can INDI or any readers of this message provide any information on what firmware versions this driver has been tested with using this mount, or with any assurance that updating the firmware will help resolve this problem?

One further question I have, assuming I can ever get connection to work, is why only EQ-N Mount setting is enabled and the others are greyed out. I would prefer Alt-Az, at least initally, as the 4SE's mount is notoriously poor at EQ mounting. Is Alt-Az mounting not supported in this INDI driver?

Thanks for your attention to this long post.