Survey the venue early
Identify the production position, cable route, available Ethernet, Wi-Fi restrictions and mobile signal for several operators. Test during a busy period when possible. A morning speed test at an empty venue may not represent conditions during the ceremony.
Carry diverse connections
Use the venue LAN when it is stable, but add mobile modems or tethered phones from independent providers. Bonding these links prevents the stream from depending entirely on a router shared with guests, caterers, payment terminals and venue staff.
Protect the physical setup
Use a powered USB hub, strain-relieve cables and keep modems where signal and ventilation are suitable. Prevent guests or crew from disturbing the network equipment. Stable power and physical connections are as important as the nominal Internet speed.
Run an end-to-end rehearsal
Stream from the actual OBS scene collection at the intended bitrate to an unlisted destination. Monitor each link and disconnect one deliberately. Confirm that remaining capacity is adequate before the ceremony begins.