If you are experiencing an issue with an Ethereum or xDai RPC endpoint when trying to bridge you can easily set your own endpoint in the interface. Note that these are Read Only, if you need to use the RPCs to process transactions, you can set custom RPCs in your web3 wallet like MetaMask as well.
Alternative Endpoint Resources
1) Go to omni.xdaichain.com and select Settings.
2) Add your RPC for either/both chains and click Save.