Please set below environment variables and run commands to test. Run these commands on command prompt or you can set it in systems environment variable:
set IBM_DB_HOME=path_to_ibm_db\installer\clidriver
set PATH=path_to_ibm_db\installer\clidriver\bin;path_to_ibm_db\installer\clidriver\lib;%PATH%
set LIB=path_to_ibm_db\installer\clidriver\lib;path_to_ibm_db\installer\clidriver\bin\icc64;%LIB%
db2trc on -f 1.trc
db2cli validate -database "sample:hotel.torolab.ibm.com:21169" -connect -user newton -passwd serverpass
db2trc off
db2trc flw 1.trc 1.flw
db2trc fmt 1.trc 1.fmt
db2trc fmt -cli 1.trc 1.cli
Update the connection information in above db2cli validate command before running it. Share the generated 1.flw, 1.fmt and 1.cli files to check for root cause of the issue. Thanks.