I found out what's likely causing those issues: https://myrepublic.net/sg/outage-not...voice-network/
Looks like it will continue to at least June 25thQuote:
We’re aware that a handful of users may have recently experienced slower connections, especially when accessing servers in the Europe and US. This is due to multiple subsea cable cuts impacting various regions, including Europe, the US, and Asia. These fiber breaks have affected our upstream provider’s partners (Telia, Telstra, NTT) and resulted in higher latency and potential connection drops when connecting to these destinations.
(I think Starhub owns MyRepublic now, so they probably have the same upstream partners)