Pick your ISP
Each hub lists every researched gateway with its verdict.
AT&T Internet
AT&T gateways document IP Passthrough (an alternative to bridge mode) rather than a bridge-mode switch.
Verizon (Fios and Home Internet)
Fios routers document DMZ host and AP-mode setups; Verizon Internet Gateways (5G/LTE Home) document IP Passthrough on LAN2.
Xfinity (Comcast)
Xfinity documents Bridge Mode on its wireless gateways, via the Admin Tool.
Spectrum (Charter)
Own modem must be on Spectrum's authorized list; 2022 moderator posts say any router is fine, combination modem/routers can be bridged, and standalone Spectrum routers cannot.
Cox
Cox documents Bridge Mode on the Panoramic Wifi Gateway, with exclusions for MoCA/IPTV and fiber (ONT) homes.
Frontier
Frontier says you may replace its router with your own, but supports only the routers it supplies.
CenturyLink / Lumen
CenturyLink's WAN settings page documents Transparent Bridging for its newer modems.
Optimum (Altice)
Optimum documents setting the TG1672 gateway's NAT to Bridged to use your own router.
Google Fiber
Google Fiber documents using your own router connected to the Fiber Jack's Ethernet port.
T-Mobile Home Internet
T-Mobile states its gateways cannot enable or disable bridge mode; third-party routers can attach via Ethernet.
Queued ISPs
No answers yet; research is queued: Windstream / Kinetic, Mediacom, WOW!, Astound Broadband, Sparklight, Ziply Fiber, Brightspeed, TDS Telecom, Metronet, Hotwire Communications, Starlink, Verizon 5G Business.