Diagnosing Hardware configuration on PPC2100 (including PLK nodes) without SDM?

Dear Experts,

I wonder if someone could give me some hints or share some ideas regarding the following situation:

We have a PPC2100 device which starts booting into AR D4.34 from a CFast card, but goes to Service mode after scanning for some remote devices.
Unfortunately, I’m unable to reach the SDM on that system!

I know the both IP addresses (ETH1 and ETH2) of the system and can ping them OK.
But the Edge browser shows the ERR_CONNECTION_REFUSED error message when I try to get to the SDM. I tried both HTTP and HTTPS…
I also tried to use telnet to check TCP ports 80 and 443 and both of them seem to be closed. So, I guess, for some reason, the SDM is disabled on this system.
Actually, it seems like the Web server has been de-activated completely.

Given that fact, what can I do to get at least some of the information that is usually seen in the Hardware page of the SDM?
Is there some workaround method to do that without SDM?

Please kindly let me know. Any advice would be highly appreciated!

Thank you and Best Regards,
Alexander K

PS. I have read this thread and followed some links. Would it help to get the $arlogsys log from the system?