Wireless Joint

If I'm using a modem with 4 MHF4 connector ports (EM20-G), how might I add the 2 additional antenna ports to the router? Could I just use 2 of the WIFI antenna slots or would I need to drill holes in the enclosure?

Unfortunately you can't reuse the existing WiFi antennas/cables since they are soldered onto the main board, but you can reuse two of their holes. Here's a couple of ways to do it.

If you're only using WiFi 2G or 5G at a time, then you could use the existing holes of the unused WiFi antennas to add two more modem antennas using two 10 inch MHF4 to SMA Female Bulkhead Straight pigtails without having to drill additional holes. You may use two 10 inch cables since a few inches shorter won't make a difference in the signal.
https://thewirelesshaven.com/shop/cables/pigtail- ... er-cables/
Also, you can reuse the two existing U.FL modem antennas without having to replace them, by using a couple of inexpensive MHF4 To U.FL Pigtail Adapter. Or replace them with two new MHF4 to SMA Female Bulkhead Straight pigtails as above.
https://thewirelesshaven.com/shop/cables/pigtail- ... l-adapter/

If you would like to use both WiFi 2G/5G at the same time, then you could simply enlarge the two existing holes on the left and right sides towards the front of the router's case, which also provides a good separation from the rest of the antennas. It's best to use the second hole from the front, so that it doesn't interfere with the main board, and install two 10 inch MHF4 to SMA Female Bulkhead Straight pigtails as above.

The third solution is to go with the new WG1608 router, which has an M.2 modem connector, and four dedicated mobile antennas with MHF4 connectors installed ready to go.
https://wirelessjoint.com/viewtopic.php?f=10&t=1172

Plenty of choices.

Thank you. Ya I actually saw your post on that new router when searching for a solution. It seems pretty enticing, but it looks like it’s only available direct from the manufacturer right now? I’m surprised GoldenOrb firmware is already available on it though. I’ll probably want to wait until there is a PoE version available, and until it’s in stock on the storefront.

thewirelesshaven0404 wrote: ↑Sun May 31, 2020 5:28 pm Thank you. Ya I actually saw your post on that new router when searching for a solution. It seems pretty enticing, but it looks like it’s only available direct from the manufacturer right now? I’m surprised GoldenOrb firmware is already available on it though. I’ll probably want to wait until there is a PoE version available, and until it’s in stock on the storefront.

Yeah it's a new device, and probably the GoldenOrb guys got one to test it. You can easily add a POE injector/splitter to make it POE, they sell those adapters in the The Wireless Haven store.