Advantech Spectre RT ERT351 Versions 5.1.3 and prior logins and passwords are transmitted in clear text form, which may allow an attacker to intercept the request.
https://us-cert.cisa.gov/ics/advisories/icsa-21-054-03
https://ep.advantech-bb.cz/support/router-models/download/511/sa-2021-01-fw-5.1.3-and-older-en.pdf