Could you please confirm whether, when setting a static IP on your PC, you specified the gateway as 192.168.1.1 (default IP)?
Also, have you tried performing a factory reset on your RUT240? Did the IP address and password revert to the default values?
Additionally, when updating via the bootloader, could you please confirm that you did not see any error messages and that the update completed successfully?
You mentioned that this is an older device. Have you used it recently, or was it unused for a long time? If it was unused, perhaps some changes were made to the default values via SDK.
If you have been using the device continuously and the issue only appeared recently, can you recall any actions performed on the device prior to the issue occurring?