Re: DrayTek routers are considered high end in the UK
I admin a prep school.
One of our remote sites runs everything over VPN (so we don't have to pay for more licenses and controllers), including telephony, via a Draytek.
Works marvellously, even if they are little clunky to configure sometimes (e.g. VLANs).
Currently running a bunch of desktops (all servers are on main site), managed switches (all uplink via the Draytek back to main site for all traffic), all the telephones (IP to main site controllers), all the CCTV (all 4K IP cameras back to main site controllers), access control (IP back to main site) and all the ancilliary little bits that go with it.
Ethernet connection over leased line, 4G backup, and (wonderfully) direct SIP access if we needed it and analogue backup for if that goes down too (meaning the Draytek is the critical 999 path for all phones on that site with no less than 4 ways to dial out). We could also use ADSL/VDSL on the same device but that would be slight overkill.
Been using similar model at home for years... literally never had a problem with it. In fact I used my freebie Draytel SIP account to show the main site SIP trunk provider how a real telephony company does things because that "just works" while theirs needed all sorts of forwards and NAT helpers and proxies and junk.
I also used their managed wireless at home and they worked just as well too.
Either they've come on since you last used them, or you chose a spectacularly bad model.