XB10: 2 Gbps symmetrical plan: download capped at ~300 M with clean signal, and Bridge Mode leaves NAT active (no DHCP lease to my router)

I upgraded to the 2 Gbps symmetrical plan this week and swapped my customer-owned DOCSIS 3.1 modem for an Xfinity XB10 (model CGM601TCOM, firmware Prod_25.1_PD, Mercer Island WA). I have two separate issues and would appreciate an Official Employee looking at the provisioning on my account.

Issue 1 — Download capped at ~300 Mbps, upload is fine (~1.8 Gbps)
Signal is now clean after I relocated the gateway next to the coax entry point (no splitters in the path):

Downstream SC-QAM: power −1.6 to −2.1 dBmV, SNR 44.5–44.7 dB, all locked, 0 uncorrectable codewords
OFDM channel 193: locked, uncorrectable codewords 7 (was 21,000+ before relocation)

Upstream: 4 SC-QAM at 37.5–39.0 dBmV, OFDMA at 33.5 dBmV, all locked
Channel 194 (second OFDM) shows all zeros — not locked or not in use
With this signal, a desktop wired directly to the gateway (2.5 GbE NIC, Wi-Fi off, Speedtest desktop app) gets ~270–300 Mbps down and ~1.8 Gbps up. The gateway has been rebooted several times. 300 Mbps looks like a provisioning tier value rather than a signal limit.

Request: please verify the provisioned download tier on my account matches the 2 Gbps plan, re-push the gateway config file, and check whether the OFDM downstream profile for channel 193 is stuck at a low profile from earlier poor-signal history.

Issue 2 — Bridge Mode on the XB10 is only half-applied
I use my own router (ASUS GT-AX11000 Pro, WAN set to DHCP). When I enable Bridge Mode in the Admin Tool:
The gateway's Wi-Fi and DHCP server turn off (expected), but routing/NAT stays on.

My router's WAN gets no lease (169.254.x.x). A desktop wired directly to the gateway with DHCP also gets 169.254.x.x and "Unable to contact your DHCP server" on ipconfig /renew.
The same desktop with a manual IP of 10.0.0.2 / gateway 10.0.0.1 does get internet — which is only possible if the gateway is still performing NAT. In true bridge mode a 10.0.0.x address could not reach the internet.
I have power-cycled the gateway for 10+ minutes with only one device connected, used the bottom 10 GbE port, and had Advanced Security off and no WiFi extenders paired. Same result every time.
Request: please check the LAN mode / bridge flag on the gateway from your side and re-push it (or provision the account with the eRouter disabled so the XB10 acts as a modem only). If true bridge mode is not currently supported on the XB10 firmware, please confirm that so I can stop troubleshooting and run DMZ instead, and please open an engineering ticket for it.

A Tier 1 chat agent today ran a line diagnostic that reported an "upstream impairment on the shared tap," but the gateway's own upstream numbers above are all normal and the download cap persists with clean signal, so I don't believe that was the cause.

Happy to provide the CM MAC and account details by direct message. Thank you.