Singtel is really bad in terms of free wireless routers given for the 3Gbps/5Gbps/10Gbps plans, especially the cheaper base plans.
Look at Starhub:
3Gbps plan --> ONT + HB410 (2.5G capable, dual 2.5G ports and dual 1G ports, dual band BE6500)
5Gbps plan --> ONT + HB710 (10G capable, dual 10G ports, triband BE18000)
10Gbps plan --> ONT + mostly EB810v (10G capable, dual 10G Ports, three 2.5G LAN ports, triband BE22000), some plans with HB710.
Look at M1:
3Gbps plan --> TP-Link Archer BE230 (2.5G capable, dual 2.5G ports, three 1G ports, dual band BE3600)
6Gbps plan --> TP-Link Archer BE805 (10G capable, dual 10G ports, four 1G ports, triband BE19000)
10Gbps plan --> Asus ZenWiFi BT10 two-pack (10G capable, dual 10G ports, one 1G port, triband BE18000) or single Archer BE805 [most of the users should get Asus ZenWiFi BT10 two-pack as the resale value is at about S$660 to S$700; Archer BE805 resale value is at about S$270 to S$300]
Now look at Singtel (all with XGS-PON ONR).
3Gbps plan --> Singtel AX5400 or HB611-SGST. Only HB611-SGST (2.5G capable, dual 2.5G ports, dual 1G ports, triband BE110000) is a good match for 3Gbps plan.
5Gbps plan --> Singtel AX5400 or HB611-SGST. HB611-SGST (only 2.5G capable) is not that good match for 5Gbps plan already but anyway still much better for Singtel AX5400.
10Gbps plan --> still HB611-SGST or HB810 (dual 10G ports, dual 2.5G ports, triband BE22000). Only HB810 is a good match for 10Gbps plan. HB611-SGST is really not a good match.