more information - https://www.bipm.org/en/about-us.
I will list only publicly avaialable servers, not the ones that require you to have prior requests for access (eg. Australia).
https://webtai.bipm.org/ftp/pub/tai/annual-reports/bipm-annual-report/TIMESERVICES/timeservices.pdf
AGGO - Argentine Observatory - German Geodesy
- ntp.aggo-conicet.gob.ar
National Geographic Institute
- ntp.ign.gob.ar
National Institute of Industrial Technology
- ntp.inti.gob.ar
Federal Office of Metrology and Surveying
- bevtime1.metrologie.at
- bevtime2.metrologie.at
- time.metrologie.at
- time.belgim.by
Royal Observatory of Belgium
- ntp1.oma.be
- ntp2.oma.be
FPS Economy
- ntp1.economie.fgov.be
- ntp2.economie.fgov.be
- ntp3.economie.fgov.be
Institute of Metrology of Bosnia and Herzegovina
- ntp1.imbih.gov.ba
- ntp2.imbih.gov.ba
PADS - Laboratory for the Processing of Analog and Digital Signals
- ntps1.pads.ufrj.br
- ntps1.cortex.pads.ufrj.br
National Observatory
- a.st1.ntp.br
- b.st1.ntp.br
- c.st1.ntp.br
- d.st1.ntp.br
- gps.ntp.br
Brazilian Time and Frequency Reference Laboratory
- 200.20.186.94
- 200.20.186.75
São Carlos Physics Institute
- lrtest1.ntp.ifsc.usp.br
- lrtest2.ntp.ifsc.usp.br
National Research Council
- time.nrc.ca
- time.chu.nrc.ca
Czech Academy of Sciences
- ntp.ufe.cz
National Institute of Metrology of China
- ntp1.nim.ac.cn
- ntp2.nim.ac.cn
National Metrology Institute
- ntp1.imbih.gov.ba
- ntp2.imbih.gov.ba
Danish National Metrology Institute
- time.dfm.dk
MIKES - Centre for Metrology and Accreditation
- time.mikes.fi
- time1.mikes.fi
- time2.mikes.fi
National Metrology and Testing Laboratory
- ntp-p1.obspm.fr
- ntp.obspm.fr
National Metrology Institute
- ptbtime1.ptb.de
- ptbtime2.ptb.de
- ptbtime3.ptb.de
- ptbtime4.ptb.de
Hellenic Institute of Metrology
- hercules.eim.gr
Hong Kong Observatory
- time.hko.hk
National Physical Laboratory
- time.nplindia.org
National Standardization Agency of Indonesia
- ntp.bsn.go.id
Istituto Nazionale di Ricerca Metrologica
- ntp1.inrim.it
- ntp1.inrim.it
- time.inrim.it
National Astronomical Observatory of Japan
- s2csntp.miz.nao.ac.jp
National Research and Development Agency
- ntp.nict.jp
Kazakhstan Institute of Standardization and Metrology
- ntp1.ksm.kz
- ntp2.ksm.kz
- ntp3.ksm.kz
Center for Physical Sciences and Technology
- laikas2.pfi.lt
- laikas2.pfi.lt
BoM - Bureau of Metrology of the Republic of Macedonia
- time.bom.gov.mk
National Metrology Institute of Malaysia
- ntp1.sirim.my
- ntp2.sirim.my
Mongolian Agency for Standardization and Metrology
- ntp.mn
National Metrology Institute
- ntp.vsl.nl
Norwegian Correctional Service
- ntp.justerveset.no
AOS - Poznan Supercomputing and Networking Centre
- vega.cbk.poznan.pl
Central Office of Measures
- tempus1.gum.gov.pl
- tempus2.gum.gov.pl
State Scientific Center of the Russian Federation
- ntp1.vniiftri.ru
- ntp2.vniiftri.ru
- ntp3.vniiftri.ru
- ntp4.vniiftri.ru
Slovenian Institute for Quality and Metrology
- ntp.siq.si
Spanish Navy Observatory
- hora.roa.es
- minuto.roa.es
National Metrology Institute of South Africa - NMISA
- time.nmisa.org
Korea Research Institute of Standards and Science
- time.kriss.re.kr
Swedish Research Institute
- ntp1.sptime.se
- ntp2.sptime.se
- ntp3.sptime.se
- ntp4.sptime.se
Netnod - Swedish Distributed Time Service
- ntp.se
Federal Institute of Metrology METAS
- ntp.metas.ch
- ntp11.metas.ch
- ntp12.metas.ch
- ntp13.metas.ch
Chunghwa Telecom Laboratories
- tock.stdtime.gov.tw
- watch.stdtime.gov.tw
- time.stdtime.gov.tw
- clock.stdtime.gov.tw
- tick.stdtime.gov.tw
National Metrology Institute
- time1.nimt.or.th
- time2.nimt.or.th
- time3.nimt.or.th
- time4.nimt.or.th
- time5.nimt.or.th
Scientific and Technological Research Council
- time.ume.tubitak.gov.tr
Institute of Metrology
- ntp.metrology.kharkov.ua
National Physical Laboratory
- ntp1.npl.co.uk
- ntp2.npl.co.uk
USNO - U.S. Naval Observatory
- tick.usno.navy.mil
- tock.usno.navy.mil
NIST
- time.nist.gov
Uzbek National Institute of Metrology
- time.nim.uz
Institute of Measurement Technology And Standards
- 222.252.20.174